auto merge of #1591 : jdm/servo/jsmanaged, r=Ms2ger

src/components/main/css/matching.rs

@@ -381,7 +381,7 @@ impl<'ln> PrivateMatchMethods for LayoutNode<'ln> {
         assert!(self.is_element());
 
         let parent_node = match parent_node {
-            Some(parent_node) if parent_node.is_element() => parent_node,
+            Some(ref parent_node) if parent_node.is_element() => parent_node,
             Some(_) | None => return None,
         };
 
@@ -455,7 +455,7 @@ impl<'ln> MatchMethods for LayoutNode<'ln> {
         }
 
         for (i, &(ref candidate, ())) in style_sharing_candidate_cache.iter().enumerate() {
-            match self.share_style_with_candidate_if_possible(parent, candidate) {
+            match self.share_style_with_candidate_if_possible(parent.clone(), candidate) {
                 Some(shared_style) => {
                     // Yay, cache hit. Share the style.
                     let mut layout_data_ref = self.mutate_layout_data();
@@ -486,7 +486,7 @@ impl<'ln> MatchMethods for LayoutNode<'ln> {
 
         // First, check to see whether we can share a style with someone.
         let sharing_result = unsafe {
-            self.share_style_if_possible(style_sharing_candidate_cache, parent)
+            self.share_style_if_possible(style_sharing_candidate_cache, parent.clone())
         };
 
         // Otherwise, match and cascade selectors.
@@ -520,7 +520,7 @@ impl<'ln> MatchMethods for LayoutNode<'ln> {
                                           initial_values,
                                           applicable_declarations_cache,
                                           style_sharing_candidate_cache,
-                                          Some(*self))
+                                          Some(self.clone()))
         }
     }
 

src/components/main/css/node_util.rs

@@ -12,10 +12,10 @@ use style::ComputedValues;
 
 pub trait NodeUtil {
     fn get_css_select_results<'a>(&'a self) -> &'a Arc<ComputedValues>;
-    fn have_css_select_results(self) -> bool;
+    fn have_css_select_results(&self) -> bool;
 
-    fn get_restyle_damage(self) -> RestyleDamage;
-    fn set_restyle_damage(self, damage: RestyleDamage);
+    fn get_restyle_damage(&self) -> RestyleDamage;
+    fn set_restyle_damage(&self, damage: RestyleDamage);
 }
 
 impl<'ln> NodeUtil for ThreadSafeLayoutNode<'ln> {
@@ -36,14 +36,14 @@ impl<'ln> NodeUtil for ThreadSafeLayoutNode<'ln> {
     }
 
     /// Does this node have a computed style yet?
-    fn have_css_select_results(self) -> bool {
+    fn have_css_select_results(&self) -> bool {
         let layout_data_ref = self.borrow_layout_data();
         layout_data_ref.get().get_ref().data.style.is_some()
     }
 
     /// Get the description of how to account for recent style changes.
     /// This is a simple bitfield and fine to copy by value.
-    fn get_restyle_damage(self) -> RestyleDamage {
+    fn get_restyle_damage(&self) -> RestyleDamage {
         // For DOM elements, if we haven't computed damage yet, assume the worst.
         // Other nodes don't have styles.
         let default = if self.node_is_element() {
@@ -63,7 +63,7 @@ impl<'ln> NodeUtil for ThreadSafeLayoutNode<'ln> {
     }
 
     /// Set the restyle damage field.
-    fn set_restyle_damage(self, damage: RestyleDamage) {
+    fn set_restyle_damage(&self, damage: RestyleDamage) {
         let mut layout_data_ref = self.mutate_layout_data();
         match *layout_data_ref.get() {
             Some(ref mut layout_data) => layout_data.data.restyle_damage = Some(damage.to_int()),

src/components/main/layout/block.rs

@@ -68,7 +68,7 @@ pub struct BlockFlow {
 }
 
 impl BlockFlow {
-    pub fn from_node(constructor: &mut FlowConstructor, node: ThreadSafeLayoutNode, is_fixed: bool)
+    pub fn from_node(constructor: &mut FlowConstructor, node: &ThreadSafeLayoutNode, is_fixed: bool)
                      -> BlockFlow {
         BlockFlow {
             base: BaseFlow::new(constructor.next_flow_id(), node),
@@ -80,7 +80,7 @@ impl BlockFlow {
     }
 
     pub fn float_from_node(constructor: &mut FlowConstructor,
-                           node: ThreadSafeLayoutNode,
+                           node: &ThreadSafeLayoutNode,
                            float_type: FloatType)
                            -> BlockFlow {
         BlockFlow {

src/components/main/layout/box_.rs

@@ -384,9 +384,9 @@ def_noncontent_horiz!(right, merge_noncontent_inline_right, clear_noncontent_inl
 
 impl Box {
     /// Constructs a new `Box` instance.
-    pub fn new(constructor: &mut FlowConstructor, node: ThreadSafeLayoutNode) -> Box {
+    pub fn new(constructor: &mut FlowConstructor, node: &ThreadSafeLayoutNode) -> Box {
         Box {
-            node: OpaqueNode::from_thread_safe_layout_node(&node),
+            node: OpaqueNode::from_thread_safe_layout_node(node),
             style: node.style().clone(),
             border_box: RefCell::new(Au::zero_rect()),
             border: RefCell::new(Zero::zero()),

src/components/main/layout/construct.rs

@@ -34,10 +34,13 @@ use layout::util::{LayoutDataAccess, OpaqueNode};
 use layout::wrapper::{PostorderNodeMutTraversal, TLayoutNode, ThreadSafeLayoutNode};
 
 use gfx::font_context::FontContext;
+use script::dom::bindings::codegen::InheritTypes::TextCast;
+use script::dom::bindings::js::JS;
 use script::dom::element::{HTMLIframeElementTypeId, HTMLImageElementTypeId, HTMLObjectElementTypeId};
 use script::dom::node::{CommentNodeTypeId, DoctypeNodeTypeId, DocumentFragmentNodeTypeId};
 use script::dom::node::{DocumentNodeTypeId, ElementNodeTypeId, ProcessingInstructionNodeTypeId};
 use script::dom::node::{TextNodeTypeId};
+use script::dom::text::Text;
 use style::computed_values::{display, position, float, white_space};
 use style::ComputedValues;
 use servo_util::namespace;
@@ -251,27 +254,27 @@ impl<'fc> FlowConstructor<'fc> {
     }
 
     /// Builds the `ImageBoxInfo` for the given image. This is out of line to guide inlining.
-    fn build_box_info_for_image(&mut self, node: ThreadSafeLayoutNode, url: Option<Url>) -> SpecificBoxInfo {
+    fn build_box_info_for_image(&mut self, node: &ThreadSafeLayoutNode, url: Option<Url>) -> SpecificBoxInfo {
         match url {
             None => GenericBox,
             Some(url) => {
                 // FIXME(pcwalton): The fact that image boxes store the cache within them makes
                 // little sense to me.
-                ImageBox(ImageBoxInfo::new(&node, url, self.layout_context.image_cache.clone()))
+                ImageBox(ImageBoxInfo::new(node, url, self.layout_context.image_cache.clone()))
             }
         }
     }
 
     /// Builds specific `Box` info for the given node.
-    pub fn build_specific_box_info_for_node(&mut self, node: ThreadSafeLayoutNode)
+    pub fn build_specific_box_info_for_node(&mut self, node: &ThreadSafeLayoutNode)
                                             -> SpecificBoxInfo {
         match node.type_id() {
             ElementNodeTypeId(HTMLImageElementTypeId) => self.build_box_info_for_image(node, node.image_url()),
-            ElementNodeTypeId(HTMLIframeElementTypeId) => IframeBox(IframeBoxInfo::new(&node)),
+            ElementNodeTypeId(HTMLIframeElementTypeId) => IframeBox(IframeBoxInfo::new(node)),
             ElementNodeTypeId(HTMLObjectElementTypeId) => {
                 self.build_box_info_for_image(node, node.get_object_data(self.url))
             }
-            TextNodeTypeId => UnscannedTextBox(UnscannedTextBoxInfo::new(&node)),
+            TextNodeTypeId => UnscannedTextBox(UnscannedTextBoxInfo::new(node)),
             _ => GenericBox,
         }
     }
@@ -284,7 +287,7 @@ impl<'fc> FlowConstructor<'fc> {
     fn flush_inline_boxes_to_flow(&mut self,
                                   boxes: ~[Box],
                                   flow: &mut ~Flow,
-                                  node: ThreadSafeLayoutNode) {
+                                  node: &ThreadSafeLayoutNode) {
         if boxes.len() == 0 {
             return
         }
@@ -301,7 +304,7 @@ impl<'fc> FlowConstructor<'fc> {
     fn flush_inline_boxes_to_flow_if_necessary(&mut self,
                                                opt_boxes: &mut Option<~[Box]>,
                                                flow: &mut ~Flow,
-                                               node: ThreadSafeLayoutNode) {
+                                               node: &ThreadSafeLayoutNode) {
         let opt_boxes = util::replace(opt_boxes, None);
         if opt_boxes.len() > 0 {
             self.flush_inline_boxes_to_flow(opt_boxes.to_vec(), flow, node)
@@ -311,7 +314,7 @@ impl<'fc> FlowConstructor<'fc> {
     /// Builds the children flows underneath a node with `display: block`. After this call,
     /// other `BlockFlow`s or `InlineFlow`s will be populated underneath this node, depending on
     /// whether {ib} splits needed to happen.
-    fn build_children_of_block_flow(&mut self, flow: &mut ~Flow, node: ThreadSafeLayoutNode) {
+    fn build_children_of_block_flow(&mut self, flow: &mut ~Flow, node: &ThreadSafeLayoutNode) {
         // Gather up boxes for the inline flows we might need to create.
         let mut opt_boxes_for_inline_flow = None;
         let mut first_box = true;
@@ -406,7 +409,7 @@ impl<'fc> FlowConstructor<'fc> {
     /// Builds a flow for a node with `display: block`. This yields a `BlockFlow` with possibly
     /// other `BlockFlow`s or `InlineFlow`s underneath it, depending on whether {ib} splits needed
     /// to happen.
-    fn build_flow_for_block(&mut self, node: ThreadSafeLayoutNode, is_fixed: bool) -> ~Flow {
+    fn build_flow_for_block(&mut self, node: &ThreadSafeLayoutNode, is_fixed: bool) -> ~Flow {
         let mut flow = ~BlockFlow::from_node(self, node, is_fixed) as ~Flow;
         self.build_children_of_block_flow(&mut flow, node);
         flow
@@ -414,7 +417,7 @@ impl<'fc> FlowConstructor<'fc> {
 
     /// Builds the flow for a node with `float: {left|right}`. This yields a float `BlockFlow` with
     /// a `BlockFlow` underneath it.
-    fn build_flow_for_floated_block(&mut self, node: ThreadSafeLayoutNode, float_type: FloatType)
+    fn build_flow_for_floated_block(&mut self, node: &ThreadSafeLayoutNode, float_type: FloatType)
                                     -> ~Flow {
         let mut flow = ~BlockFlow::float_from_node(self, node, float_type) as ~Flow;
         self.build_children_of_block_flow(&mut flow, node);
@@ -425,7 +428,7 @@ impl<'fc> FlowConstructor<'fc> {
     /// Concatenates the boxes of kids, adding in our own borders/padding/margins if necessary.
     /// Returns the `InlineBoxesConstructionResult`, if any. There will be no
     /// `InlineBoxesConstructionResult` if this node consisted entirely of ignorable whitespace.
-    fn build_boxes_for_nonreplaced_inline_content(&mut self, node: ThreadSafeLayoutNode)
+    fn build_boxes_for_nonreplaced_inline_content(&mut self, node: &ThreadSafeLayoutNode)
                                                   -> ConstructionResult {
         let mut opt_inline_block_splits = None;
         let mut opt_box_accumulator = None;
@@ -542,7 +545,7 @@ impl<'fc> FlowConstructor<'fc> {
 
     fn set_inline_info_for_inline_child(&mut self,
                                         boxes: &~[&Box],
-                                        parent_node: ThreadSafeLayoutNode) {
+                                        parent_node: &ThreadSafeLayoutNode) {
         let parent_box = Box::new(self, parent_node);
         let font_style = parent_box.font_style();
         let font_group = self.font_context.get_resolved_font_for_style(&font_style);
@@ -580,7 +583,7 @@ impl<'fc> FlowConstructor<'fc> {
                             style: parent_box.style.clone(),
                             font_ascent: font_ascent,
                             font_descent: font_descent,
-                            node: OpaqueNode::from_thread_safe_layout_node(&parent_node),
+                            node: OpaqueNode::from_thread_safe_layout_node(parent_node),
                         });
                 },
                 &None => {}
@@ -589,7 +592,7 @@ impl<'fc> FlowConstructor<'fc> {
     }
     /// Creates an `InlineBoxesConstructionResult` for replaced content. Replaced content doesn't
     /// render its children, so this just nukes a child's boxes and creates a `Box`.
-    fn build_boxes_for_replaced_inline_content(&mut self, node: ThreadSafeLayoutNode)
+    fn build_boxes_for_replaced_inline_content(&mut self, node: &ThreadSafeLayoutNode)
                                                -> ConstructionResult {
         for kid in node.children() {
             kid.set_flow_construction_result(NoConstructionResult)
@@ -597,7 +600,7 @@ impl<'fc> FlowConstructor<'fc> {
 
         // If this node is ignorable whitespace, bail out now.
         if node.is_ignorable_whitespace() {
-            let opaque_node = OpaqueNode::from_thread_safe_layout_node(&node);
+            let opaque_node = OpaqueNode::from_thread_safe_layout_node(node);
             return ConstructionItemConstructionResult(WhitespaceConstructionItem(
                 opaque_node,
                 node.style().clone()))
@@ -614,7 +617,7 @@ impl<'fc> FlowConstructor<'fc> {
 
     /// Builds one or more boxes for a node with `display: inline`. This yields an
     /// `InlineBoxesConstructionResult`.
-    fn build_boxes_for_inline(&mut self, node: ThreadSafeLayoutNode) -> ConstructionResult {
+    fn build_boxes_for_inline(&mut self, node: &ThreadSafeLayoutNode) -> ConstructionResult {
         // Is this node replaced content?
         if !node.is_replaced_content() {
             // Go to a path that concatenates our kids' boxes.
@@ -630,7 +633,7 @@ impl<'a> PostorderNodeMutTraversal for FlowConstructor<'a> {
     // `#[inline(always)]` because this is always called from the traversal function and for some
     // reason LLVM's inlining heuristics go awry here.
     #[inline(always)]
-    fn process(&mut self, node: ThreadSafeLayoutNode) -> bool {
+    fn process(&mut self, node: &ThreadSafeLayoutNode) -> bool {
         // Get the `display` property for this node, and determine whether this node is floated.
         let (display, float, position) = match node.type_id() {
             ElementNodeTypeId(_) => {
@@ -693,21 +696,21 @@ impl<'a> PostorderNodeMutTraversal for FlowConstructor<'a> {
 /// A utility trait with some useful methods for node queries.
 trait NodeUtils {
     /// Returns true if this node doesn't render its kids and false otherwise.
-    fn is_replaced_content(self) -> bool;
+    fn is_replaced_content(&self) -> bool;
 
     /// Returns true if this node is ignorable whitespace.
-    fn is_ignorable_whitespace(self) -> bool;
+    fn is_ignorable_whitespace(&self) -> bool;
 
     /// Sets the construction result of a flow.
-    fn set_flow_construction_result(self, result: ConstructionResult);
+    fn set_flow_construction_result(&self, result: ConstructionResult);
 
     /// Replaces the flow construction result in a node with `NoConstructionResult` and returns the
     /// old value.
-    fn swap_out_construction_result(self) -> ConstructionResult;
+    fn swap_out_construction_result(&self) -> ConstructionResult;
 }
 
 impl<'ln> NodeUtils for ThreadSafeLayoutNode<'ln> {
-    fn is_replaced_content(self) -> bool {
+    fn is_replaced_content(&self) -> bool {
         match self.type_id() {
             TextNodeTypeId |
             ProcessingInstructionNodeTypeId |
@@ -721,11 +724,12 @@ impl<'ln> NodeUtils for ThreadSafeLayoutNode<'ln> {
         }
     }
 
-    fn is_ignorable_whitespace(self) -> bool {
+    fn is_ignorable_whitespace(&self) -> bool {
         match self.type_id() {
             TextNodeTypeId => {
                 unsafe {
-                    if !self.with_text(|text| is_whitespace(text.characterdata.data)) {
+                    let text: JS<Text> = TextCast::to(self.get_jsmanaged());
+                    if !is_whitespace(text.get().characterdata.data) {
                         return false
                     }
 
@@ -746,7 +750,7 @@ impl<'ln> NodeUtils for ThreadSafeLayoutNode<'ln> {
     }
 
     #[inline(always)]
-    fn set_flow_construction_result(self, result: ConstructionResult) {
+    fn set_flow_construction_result(&self, result: ConstructionResult) {
         let mut layout_data_ref = self.mutate_layout_data();
         match *layout_data_ref.get() {
             Some(ref mut layout_data) => layout_data.data.flow_construction_result = result,
@@ -755,7 +759,7 @@ impl<'ln> NodeUtils for ThreadSafeLayoutNode<'ln> {
     }
 
     #[inline(always)]
-    fn swap_out_construction_result(self) -> ConstructionResult {
+    fn swap_out_construction_result(&self) -> ConstructionResult {
         let mut layout_data_ref = self.mutate_layout_data();
         match *layout_data_ref.get() {
             Some(ref mut layout_data) => {
@@ -769,29 +773,29 @@ impl<'ln> NodeUtils for ThreadSafeLayoutNode<'ln> {
 /// Methods for interacting with HTMLObjectElement nodes
 trait ObjectElement {
     /// Returns None if this node is not matching attributes.
-    fn get_type_and_data(self) -> (Option<&'static str>, Option<&'static str>);
+    fn get_type_and_data(&self) -> (Option<&'static str>, Option<&'static str>);
 
     /// Returns true if this node has object data that is correct uri.
-    fn has_object_data(self) -> bool;
+    fn has_object_data(&self) -> bool;
 
     /// Returns the "data" attribute value parsed as a URL    
-    fn get_object_data(self, base_url: &Url) -> Option<Url>;
+    fn get_object_data(&self, base_url: &Url) -> Option<Url>;
 }
 
 impl<'ln> ObjectElement for ThreadSafeLayoutNode<'ln> {
-    fn get_type_and_data(self) -> (Option<&'static str>, Option<&'static str>) {
+    fn get_type_and_data(&self) -> (Option<&'static str>, Option<&'static str>) {
         (self.with_element(|e| { e.get_attr(&namespace::Null, "type") } ),
         self.with_element(|e| { e.get_attr(&namespace::Null, "data") } ))
     }
 
-    fn has_object_data(self) -> bool {
+    fn has_object_data(&self) -> bool {
         match self.get_type_and_data() {
             (None, Some(uri)) => is_image_data(uri),
             _ => false
         }   
     }
 
-    fn get_object_data(self, base_url: &Url) -> Option<Url> {
+    fn get_object_data(&self, base_url: &Url) -> Option<Url> {
         match self.get_type_and_data() {
             (None, Some(uri)) if is_image_data(uri) => Some(parse_url(uri, Some(base_url.clone()))),
             _ => None

src/components/main/layout/extra.rs

@@ -10,15 +10,15 @@ use script::layout_interface::LayoutChan;
 
 /// Functionality useful for querying the layout-specific data on DOM nodes.
 pub trait LayoutAuxMethods {
-    fn initialize_layout_data(self, chan: LayoutChan);
-    fn initialize_style_for_subtree(self, chan: LayoutChan);
+    fn initialize_layout_data(&self, chan: LayoutChan);
+    fn initialize_style_for_subtree(&self, chan: LayoutChan);
 }
 
 impl<'ln> LayoutAuxMethods for LayoutNode<'ln> {
     /// Resets layout data and styles for the node.
     ///
     /// FIXME(pcwalton): Do this as part of box building instead of in a traversal.
-    fn initialize_layout_data(self, chan: LayoutChan) {
+    fn initialize_layout_data(&self, chan: LayoutChan) {
         let mut layout_data_ref = self.mutate_layout_data();
         match *layout_data_ref.get() {
             None => {
@@ -34,7 +34,7 @@ impl<'ln> LayoutAuxMethods for LayoutNode<'ln> {
     /// Resets layout data and styles for a Node tree.
         ///
     /// FIXME(pcwalton): Do this as part of box building instead of in a traversal.
-    fn initialize_style_for_subtree(self, chan: LayoutChan) {
+    fn initialize_style_for_subtree(&self, chan: LayoutChan) {
         for n in self.traverse_preorder() {
             n.initialize_layout_data(chan.clone());
         }

src/components/main/layout/flow.rs

@@ -563,7 +563,7 @@ impl Iterator<@Box> for BoxIterator {
 
 impl BaseFlow {
     #[inline]
-    pub fn new(id: int, node: ThreadSafeLayoutNode) -> BaseFlow {
+    pub fn new(id: int, node: &ThreadSafeLayoutNode) -> BaseFlow {
         let style = node.style();
         BaseFlow {
             restyle_damage: node.restyle_damage(),

src/components/main/layout/inline.rs

@@ -466,7 +466,7 @@ pub struct InlineFlow {
 }
 
 impl InlineFlow {
-    pub fn from_boxes(id: int, node: ThreadSafeLayoutNode, boxes: ~[Box]) -> InlineFlow {
+    pub fn from_boxes(id: int, node: &ThreadSafeLayoutNode, boxes: ~[Box]) -> InlineFlow {
         InlineFlow {
             base: BaseFlow::new(id, node),
             boxes: boxes,

src/components/main/layout/layout_task.rs

@@ -17,7 +17,7 @@ use layout::flow::{PreorderFlowTraversal, PostorderFlowTraversal};
 use layout::flow;
 use layout::incremental::RestyleDamage;
 use layout::parallel::{AssignHeightsAndStoreOverflowTraversalKind, BubbleWidthsTraversalKind};
-use layout::parallel::{UnsafeFlow};
+use layout::parallel::{PaddedUnsafeFlow};
 use layout::parallel;
 use layout::util::{LayoutDataAccess, OpaqueNode, LayoutDataWrapper};
 use layout::wrapper::{DomLeafSet, LayoutNode, TLayoutNode, ThreadSafeLayoutNode};
@@ -32,8 +32,9 @@ use gfx::font_context::FontContextInfo;
 use gfx::opts::Opts;
 use gfx::render_task::{RenderMsg, RenderChan, RenderLayer};
 use gfx::{render_task, color};
+use script::dom::bindings::js::JS;
 use script::dom::event::ReflowEvent;
-use script::dom::node::{ElementNodeTypeId, LayoutDataRef};
+use script::dom::node::{ElementNodeTypeId, LayoutDataRef, Node};
 use script::dom::element::{HTMLBodyElementTypeId, HTMLHtmlElementTypeId};
 use script::layout_interface::{AddStylesheetMsg, ContentBoxQuery};
 use script::layout_interface::{ContentBoxesQuery, ContentBoxesResponse, ExitNowMsg, LayoutQuery};
@@ -104,7 +105,7 @@ pub struct LayoutTask {
     initial_css_values: Arc<ComputedValues>,
 
     /// The workers that we use for parallel operation.
-    parallel_traversal: Option<WorkQueue<*mut LayoutContext,UnsafeFlow>>,
+    parallel_traversal: Option<WorkQueue<*mut LayoutContext,PaddedUnsafeFlow>>,
 
     /// The channel on which messages can be sent to the profiler.
     profiler_chan: ProfilerChan,
@@ -429,8 +430,8 @@ impl LayoutTask {
     /// is intertwined with selector matching, making it difficult to compare directly. It is
     /// marked `#[inline(never)]` to aid benchmarking in sampling profilers.
     #[inline(never)]
-    fn construct_flow_tree(&self, layout_context: &mut LayoutContext, node: LayoutNode, url: &Url) -> ~Flow {
-        let node = ThreadSafeLayoutNode::new(node);
+    fn construct_flow_tree(&self, layout_context: &mut LayoutContext, node: &mut LayoutNode, url: &Url) -> ~Flow {
+        let mut node = ThreadSafeLayoutNode::new(node);
         node.traverse_postorder_mut(&mut FlowConstructor::init(layout_context, url));
 
         let mut layout_data_ref = node.mutate_layout_data();
@@ -527,8 +528,9 @@ impl LayoutTask {
     /// The high-level routine that performs layout tasks.
     fn handle_reflow(&mut self, data: &Reflow) {
         // FIXME: Isolate this transmutation into a "bridge" module.
-        let node: &LayoutNode = unsafe {
-            transmute(&data.document_root)
+        let node: &mut LayoutNode = unsafe {
+            let mut node: JS<Node> = JS::from_trusted_node_address(data.document_root);
+            transmute(&mut node)
         };
 
         debug!("layout: received layout request for: {:s}", data.url.to_str());
@@ -596,7 +598,7 @@ impl LayoutTask {
             // Construct the flow tree.
             profile(time::LayoutTreeBuilderCategory,
                     self.profiler_chan.clone(),
-                    || self.construct_flow_tree(&mut layout_ctx, *node, &data.url))
+                    || self.construct_flow_tree(&mut layout_ctx, node, &data.url))
         });
 
         // Verification of the flow tree, which ensures that all nodes were either marked as leaves
@@ -648,7 +650,7 @@ impl LayoutTask {
                     if child.type_id() == ElementNodeTypeId(HTMLHtmlElementTypeId) || 
                             child.type_id() == ElementNodeTypeId(HTMLBodyElementTypeId) {
                         let element_bg_color = {
-                            let thread_safe_child = ThreadSafeLayoutNode::new(child);
+                            let thread_safe_child = ThreadSafeLayoutNode::new(&child);
                             thread_safe_child.style()
                                              .get()
                                              .resolve_color(thread_safe_child.style()
@@ -700,7 +702,7 @@ impl LayoutTask {
             // The neat thing here is that in order to answer the following two queries we only
             // need to compare nodes for equality. Thus we can safely work only with `OpaqueNode`.
             ContentBoxQuery(node, reply_chan) => {
-                let node = OpaqueNode::from_script_node(&node);
+                let node = OpaqueNode::from_script_node(node);
 
                 fn union_boxes_for_node<'a>(
                                         accumulator: &mut Option<Rect<Au>>,
@@ -724,7 +726,7 @@ impl LayoutTask {
                 reply_chan.send(ContentBoxResponse(rect.unwrap_or(Au::zero_rect())))
             }
             ContentBoxesQuery(node, reply_chan) => {
-                let node = OpaqueNode::from_script_node(&node);
+                let node = OpaqueNode::from_script_node(node);
 
                 fn add_boxes_for_node<'a>(
                                       accumulator: &mut ~[Rect<Au>],

src/components/main/layout/parallel.rs

@@ -29,6 +29,36 @@ pub enum TraversalKind {
     AssignHeightsAndStoreOverflowTraversalKind,
 }
 
+#[allow(dead_code)]
+fn static_assertion(node: UnsafeLayoutNode) {
+    unsafe {
+        let _: PaddedUnsafeFlow = ::std::unstable::intrinsics::transmute(node);
+    }
+}
+
+/// Memory representation that is at least as large as UnsafeLayoutNode, as it must be
+/// safely transmutable to and from that type to accommodate the type-unsafe parallel work
+/// queue usage that stores both flows and nodes.
+pub type PaddedUnsafeFlow = (uint, uint, uint);
+
+trait UnsafeFlowConversions {
+    fn to_flow(&self) -> UnsafeFlow;
+    fn from_flow(flow: &UnsafeFlow) -> Self;
+}
+
+impl UnsafeFlowConversions for PaddedUnsafeFlow {
+    fn to_flow(&self) -> UnsafeFlow {
+        let (vtable, ptr, _padding) = *self;
+        (vtable, ptr)
+    }
+
+    fn from_flow(flow: &UnsafeFlow) -> PaddedUnsafeFlow {
+        let &(vtable, ptr) = flow;
+        (vtable, ptr, 0)
+    }
+}
+
+/// Vtable + pointer representation of a Flow trait object.
 pub type UnsafeFlow = (uint, uint);
 
 fn null_unsafe_flow() -> UnsafeFlow {
@@ -141,7 +171,7 @@ fn match_and_cascade_node(unsafe_layout_node: UnsafeLayoutNode,
         let layout_context: &mut LayoutContext = cast::transmute(*proxy.user_data());
 
         // Get a real layout node.
-        let node: LayoutNode = cast::transmute(unsafe_layout_node);
+        let node: LayoutNode = ::std::unstable::intrinsics::transmute(unsafe_layout_node);
 
         // Initialize layout data.
         //
@@ -159,7 +189,7 @@ fn match_and_cascade_node(unsafe_layout_node: UnsafeLayoutNode,
         // First, check to see whether we can share a style with someone.
         let style_sharing_candidate_cache = layout_context.style_sharing_candidate_cache();
         let sharing_result = node.share_style_if_possible(style_sharing_candidate_cache,
-                                                          parent_opt);
+                                                          parent_opt.clone());
 
         // Otherwise, match and cascade selectors.
         match sharing_result {
@@ -215,25 +245,25 @@ fn match_and_cascade_node(unsafe_layout_node: UnsafeLayoutNode,
     }
 }
 
-fn bubble_widths(unsafe_flow: UnsafeFlow, proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeFlow>) {
+fn bubble_widths(unsafe_flow: PaddedUnsafeFlow, proxy: &mut WorkerProxy<*mut LayoutContext,PaddedUnsafeFlow>) {
     let layout_context: &mut LayoutContext = unsafe {
         cast::transmute(*proxy.user_data())
     };
     let mut bubble_widths_traversal = BubbleWidthsTraversal {
         layout_context: layout_context,
     };
-    bubble_widths_traversal.run_parallel(unsafe_flow)
+    bubble_widths_traversal.run_parallel(unsafe_flow.to_flow())
 }
 
-fn assign_heights_and_store_overflow(unsafe_flow: UnsafeFlow,
-                                     proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeFlow>) {
+fn assign_heights_and_store_overflow(unsafe_flow: PaddedUnsafeFlow,
+                                     proxy: &mut WorkerProxy<*mut LayoutContext,PaddedUnsafeFlow>) {
     let layout_context: &mut LayoutContext = unsafe {
         cast::transmute(*proxy.user_data())
     };
     let mut assign_heights_traversal = AssignHeightsAndStoreOverflowTraversal {
         layout_context: layout_context,
     };
-    assign_heights_traversal.run_parallel(unsafe_flow)
+    assign_heights_traversal.run_parallel(unsafe_flow.to_flow())
 }
 
 pub fn match_and_cascade_subtree(root_node: &LayoutNode,
@@ -258,7 +288,7 @@ pub fn traverse_flow_tree(kind: TraversalKind,
                           leaf_set: &Arc<FlowLeafSet>,
                           profiler_chan: ProfilerChan,
                           layout_context: &mut LayoutContext,
-                          queue: &mut WorkQueue<*mut LayoutContext,UnsafeFlow>) {
+                          queue: &mut WorkQueue<*mut LayoutContext,PaddedUnsafeFlow>) {
     unsafe {
         queue.data = cast::transmute(layout_context)
     }
@@ -272,7 +302,7 @@ pub fn traverse_flow_tree(kind: TraversalKind,
         for (flow, _) in leaf_set.get().iter() {
             queue.push(WorkUnit {
                 fun: fun,
-                data: *flow,
+                data: UnsafeFlowConversions::from_flow(flow),
             })
         }
     });

src/components/main/layout/util.rs

@@ -8,9 +8,10 @@ use layout::parallel::DomParallelInfo;
 use layout::wrapper::{LayoutNode, TLayoutNode, ThreadSafeLayoutNode};
 
 use extra::arc::Arc;
+use script::dom::bindings::js::JS;
 use script::dom::bindings::utils::Reflectable;
-use script::dom::node::AbstractNode;
-use script::layout_interface::{LayoutChan, UntrustedNodeAddress};
+use script::dom::node::Node;
+use script::layout_interface::{LayoutChan, UntrustedNodeAddress, TrustedNodeAddress};
 use servo_util::range::Range;
 use std::cast;
 use std::cell::{Ref, RefMut};
@@ -212,23 +213,28 @@ impl OpaqueNode {
     /// Converts a DOM node (layout view) to an `OpaqueNode`.
     pub fn from_layout_node(node: &LayoutNode) -> OpaqueNode {
         unsafe {
-            let abstract_node = node.get_abstract();
-            let ptr: uintptr_t = cast::transmute(abstract_node.reflector().get_jsobject());
-            OpaqueNode(ptr)
+            OpaqueNode::from_jsmanaged(node.get_jsmanaged())
         }
     }
 
     /// Converts a thread-safe DOM node (layout view) to an `OpaqueNode`.
     pub fn from_thread_safe_layout_node(node: &ThreadSafeLayoutNode) -> OpaqueNode {
         unsafe {
-            let abstract_node = node.get_abstract();
+            let abstract_node = node.get_jsmanaged();
             let ptr: uintptr_t = cast::transmute(abstract_node.reflector().get_jsobject());
             OpaqueNode(ptr)
         }
     }
 
     /// Converts a DOM node (script view) to an `OpaqueNode`.
-    pub fn from_script_node(node: &AbstractNode) -> OpaqueNode {
+    pub fn from_script_node(node: TrustedNodeAddress) -> OpaqueNode {
+        unsafe {
+            OpaqueNode::from_jsmanaged(&JS::from_trusted_node_address(node))
+        }
+    }
+
+    /// Converts a DOM node to an `OpaqueNode'.
+    fn from_jsmanaged(node: &JS<Node>) -> OpaqueNode {
         unsafe {
             let ptr: uintptr_t = cast::transmute(node.reflector().get_jsobject());
             OpaqueNode(ptr)

src/components/main/layout/wrapper.rs

@@ -11,15 +11,18 @@
 //!
 //! (1) Layout is not allowed to mutate the DOM.
 //!
-//! (2) Layout is not allowed to see anything with `Abstract` in the name, because it could hang
+//! (2) Layout is not allowed to see anything with `JS` in the name, because it could hang
 //!     onto these objects and cause use-after-free.
 
 use extra::url::Url;
+use script::dom::bindings::codegen::InheritTypes::{HTMLImageElementCast, HTMLIFrameElementCast};
+use script::dom::bindings::codegen::InheritTypes::{TextCast, ElementCast};
+use script::dom::bindings::js::JS;
 use script::dom::element::{Element, HTMLAreaElementTypeId, HTMLAnchorElementTypeId};
 use script::dom::element::{HTMLLinkElementTypeId};
 use script::dom::htmliframeelement::HTMLIFrameElement;
 use script::dom::htmlimageelement::HTMLImageElement;
-use script::dom::node::{AbstractNode, DocumentNodeTypeId, ElementNodeTypeId, Node, NodeTypeId};
+use script::dom::node::{DocumentNodeTypeId, ElementNodeTypeId, Node, NodeTypeId, NodeHelpers};
 use script::dom::text::Text;
 use servo_msg::constellation_msg::{PipelineId, SubpageId};
 use servo_util::concurrentmap::{ConcurrentHashMap, ConcurrentHashMapIterator};
@@ -35,20 +38,20 @@ use layout::util::LayoutDataWrapper;
 /// Allows some convenience methods on generic layout nodes.
 pub trait TLayoutNode {
     /// Creates a new layout node with the same lifetime as this layout node.
-    unsafe fn new_with_this_lifetime(&self, node: AbstractNode) -> Self;
+    unsafe fn new_with_this_lifetime(&self, node: JS<Node>) -> Self;
 
     /// Returns the type ID of this node. Fails if this node is borrowed mutably.
     fn type_id(&self) -> NodeTypeId;
 
-    /// Returns the interior of this node as an `AbstractNode`. This is highly unsafe for layout to
+
+    /// Returns the interior of this node as a `JS`. This is highly unsafe for layout to
     /// call and as such is marked `unsafe`.
-    unsafe fn get_abstract(&self) -> AbstractNode;
+    unsafe fn get_jsmanaged<'a>(&'a self) -> &'a JS<Node>;
 
     /// Returns the interior of this node as a `Node`. This is highly unsafe for layout to call
     /// and as such is marked `unsafe`.
     unsafe fn get<'a>(&'a self) -> &'a Node {
-        let node = self.get_abstract();
-        cast::transmute(node.node())
+        self.get_jsmanaged().get()
     }
 
     fn node_is_element(&self) -> bool {
@@ -70,40 +73,18 @@ pub trait TLayoutNode {
     /// FIXME(pcwalton): Don't copy URLs.
     fn image_url(&self) -> Option<Url> {
         unsafe {
-            self.with_image_element(|image_element| {
-                image_element.image.as_ref().map(|url| (*url).clone())
-            })
+            let image_element: JS<HTMLImageElement> = HTMLImageElementCast::to(self.get_jsmanaged());
+            image_element.get().extra.image.as_ref().map(|url| (*url).clone())
         }
     }
 
-    /// Downcasts this node to an iframe element and calls the given closure.
-    ///
-    /// FIXME(pcwalton): RAII.
-    unsafe fn with_iframe_element<R>(&self, f: |&HTMLIFrameElement| -> R) -> R {
-        if !self.get_abstract().is_iframe_element() {
-            fail!(~"node is not an iframe element");
-        }
-        self.get_abstract().transmute(f)
-    }
-
-    /// Downcasts this node to an image element and calls the given closure.
-    ///
-    /// FIXME(pcwalton): RAII.
-    unsafe fn with_image_element<R>(&self, f: |&HTMLImageElement| -> R) -> R {
-        if !self.get_abstract().is_image_element() {
-            fail!(~"node is not an image element");
-        }
-        self.get_abstract().transmute(f)
-    }
-
     /// If this node is an iframe element, returns its pipeline and subpage IDs. If this node is
     /// not an iframe element, fails.
     fn iframe_pipeline_and_subpage_ids(&self) -> (PipelineId, SubpageId) {
         unsafe {
-            self.with_iframe_element(|iframe_element| {
-                let size = iframe_element.size.unwrap();
+            let iframe_element: JS<HTMLIFrameElement> = HTMLIFrameElementCast::to(self.get_jsmanaged());
+            let size = iframe_element.get().size.unwrap();
             (size.pipeline_id, size.subpage_id)
-            })
         }
     }
 
@@ -112,45 +93,39 @@ pub trait TLayoutNode {
     /// FIXME(pcwalton): Don't copy text. Atomically reference count instead.
     fn text(&self) -> ~str {
         unsafe {
-            self.with_text(|text| text.characterdata.data.to_str())
+            let text: JS<Text> = TextCast::to(self.get_jsmanaged());
+            text.get().characterdata.data.to_str()
         }
     }
 
-    /// Downcasts this node to a text node and calls the given closure.
-    ///
-    /// FIXME(pcwalton): RAII.
-    unsafe fn with_text<R>(&self, f: |&Text| -> R) -> R {
-        self.get_abstract().with_imm_text(f)
-    }
-
     /// Returns the first child of this node.
     fn first_child(&self) -> Option<Self> {
         unsafe {
-            self.get_abstract().first_child().map(|node| self.new_with_this_lifetime(node))
+            self.get_jsmanaged().first_child().map(|node| self.new_with_this_lifetime(node))
         }
     }
 
     /// Dumps this node tree, for debugging.
     fn dump(&self) {
         unsafe {
-            self.get_abstract().dump()
+            self.get_jsmanaged().dump()
         }
     }
 }
 
 /// A wrapper so that layout can access only the methods that it should have access to. Layout must
-/// only ever see these and must never see instances of `AbstractNode`.
+/// only ever see these and must never see instances of `JS`.
 #[deriving(Clone, Eq)]
 pub struct LayoutNode<'a> {
     /// The wrapped node.
-    priv node: AbstractNode,
+    priv node: JS<Node>,
 
     /// Being chained to a value prevents `LayoutNode`s from escaping.
     priv chain: &'a (),
 }
 
 impl<'ln> TLayoutNode for LayoutNode<'ln> {
-    unsafe fn new_with_this_lifetime(&self, node: AbstractNode) -> LayoutNode<'ln> {
+    unsafe fn new_with_this_lifetime(&self, node: JS<Node>) -> LayoutNode<'ln> {
         LayoutNode {
             node: node,
             chain: self.chain,
@@ -159,14 +134,14 @@ impl<'ln> TLayoutNode for LayoutNode<'ln> {
     fn type_id(&self) -> NodeTypeId {
         self.node.type_id()
     }
-    unsafe fn get_abstract(&self) -> AbstractNode {
-        self.node
+    unsafe fn get_jsmanaged<'a>(&'a self) -> &'a JS<Node> {
+        &self.node
     }
 }
 
 impl<'ln> LayoutNode<'ln> {
     /// Creates a new layout node, scoped to the given closure.
-    pub unsafe fn with_layout_node<R>(node: AbstractNode, f: <'a> |LayoutNode<'a>| -> R) -> R {
+    pub unsafe fn with_layout_node<R>(node: JS<Node>, f: <'a> |LayoutNode<'a>| -> R) -> R {
         let heavy_iron_ball = ();
         f(LayoutNode {
             node: node,
@@ -194,26 +169,27 @@ impl<'ln> LayoutNode<'ln> {
 impl<'ln> TNode<LayoutElement<'ln>> for LayoutNode<'ln> {
     fn parent_node(&self) -> Option<LayoutNode<'ln>> {
         unsafe {
-            self.node.node().parent_node.map(|node| self.new_with_this_lifetime(node))
+            self.node.parent_node().map(|node| self.new_with_this_lifetime(node))
         }
     }
 
     fn prev_sibling(&self) -> Option<LayoutNode<'ln>> {
         unsafe {
-            self.node.node().prev_sibling.map(|node| self.new_with_this_lifetime(node))
+            self.node.prev_sibling().map(|node| self.new_with_this_lifetime(node))
         }
     }
 
     fn next_sibling(&self) -> Option<LayoutNode<'ln>> {
         unsafe {
-            self.node.node().next_sibling.map(|node| self.new_with_this_lifetime(node))
+            self.node.next_sibling().map(|node| self.new_with_this_lifetime(node))
         }
     }
 
     /// If this is an element, accesses the element data. Fails if this is not an element node.
     #[inline]
     fn with_element<R>(&self, f: |&LayoutElement<'ln>| -> R) -> R {
-        self.node.with_imm_element(|element| {
+        let elem: JS<Element> = ElementCast::to(&self.node);
+        let element = elem.get();
         // FIXME(pcwalton): Workaround until Rust gets multiple lifetime parameters on
         // implementations.
         unsafe {
@@ -221,7 +197,6 @@ impl<'ln> TNode<LayoutElement<'ln>> for LayoutNode<'ln> {
                 element: cast::transmute_region(element),
             })
         }
-        })
     }
 
     fn is_element(&self) -> bool {
@@ -257,8 +232,8 @@ pub struct LayoutNodeChildrenIterator<'a> {
 
 impl<'a> Iterator<LayoutNode<'a>> for LayoutNodeChildrenIterator<'a> {
     fn next(&mut self) -> Option<LayoutNode<'a>> {
-        let node = self.current_node;
-        self.current_node = self.current_node.and_then(|node| {
+        let node = self.current_node.clone();
+        self.current_node = node.clone().and_then(|node| {
             node.next_sibling()
         });
         node
@@ -358,7 +333,7 @@ impl<'le> TElement for LayoutElement<'le> {
 /// node does not allow any parents or siblings of nodes to be accessed, to avoid races.
 pub struct ThreadSafeLayoutNode<'ln> {
     /// The wrapped node.
-    priv node: AbstractNode,
+    priv node: JS<Node>,
 
     /// Being chained to a value prevents `ThreadSafeLayoutNode`s from escaping.
     priv chain: &'ln (),
@@ -366,7 +341,7 @@ pub struct ThreadSafeLayoutNode<'ln> {
 
 impl<'ln> TLayoutNode for ThreadSafeLayoutNode<'ln> {
     /// Creates a new layout node with the same lifetime as this layout node.
-    unsafe fn new_with_this_lifetime(&self, node: AbstractNode) -> ThreadSafeLayoutNode<'ln> {
+    unsafe fn new_with_this_lifetime(&self, node: JS<Node>) -> ThreadSafeLayoutNode<'ln> {
         ThreadSafeLayoutNode {
             node: node,
             chain: self.chain,
@@ -375,23 +350,32 @@ impl<'ln> TLayoutNode for ThreadSafeLayoutNode<'ln> {
     fn type_id(&self) -> NodeTypeId {
         self.node.type_id()
     }
-    unsafe fn get_abstract(&self) -> AbstractNode {
-        self.node
+    unsafe fn get_jsmanaged<'a>(&'a self) -> &'a JS<Node> {
+        &self.node
+    }
+}
+
+impl<'ln> Clone for ThreadSafeLayoutNode<'ln> {
+    fn clone(&self) -> ThreadSafeLayoutNode<'ln> {
+        ThreadSafeLayoutNode {
+            node: self.node.clone(),
+            chain: self.chain,
+        }
     }
 }
 
 impl<'ln> ThreadSafeLayoutNode<'ln> {
     /// Creates a new `ThreadSafeLayoutNode` from the given `LayoutNode`.
-    pub fn new<'a>(node: LayoutNode<'a>) -> ThreadSafeLayoutNode<'a> {
+    pub fn new<'a>(node: &LayoutNode<'a>) -> ThreadSafeLayoutNode<'a> {
         ThreadSafeLayoutNode {
-            node: node.node,
+            node: node.node.clone(),
             chain: node.chain,
         }
     }
 
     /// Returns the next sibling of this node. Unsafe and private because this can lead to races.
     unsafe fn next_sibling(&self) -> Option<ThreadSafeLayoutNode<'ln>> {
-        self.node.node().next_sibling.map(|node| self.new_with_this_lifetime(node))
+        self.node.next_sibling().map(|node| self.new_with_this_lifetime(node))
     }
 
     /// Returns an iterator over this node's children.
@@ -405,13 +389,13 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
     #[inline]
     pub fn with_element<R>(&self, f: |&ThreadSafeLayoutElement| -> R) -> R {
         unsafe {
-            self.get_abstract().with_imm_element(|element| {
+            let elem: JS<Element> = ElementCast::to(&self.node);
+            let element = elem.get();
             // FIXME(pcwalton): Workaround until Rust gets multiple lifetime parameters on
             // implementations.
             f(&ThreadSafeLayoutElement {
                 element: cast::transmute_region(element),
             })
-            })
         }
     }
 
@@ -434,7 +418,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
     /// Traverses the tree in postorder.
     ///
     /// TODO(pcwalton): Offer a parallel version with a compatible API.
-    pub fn traverse_postorder_mut<T:PostorderNodeMutTraversal>(mut self, traversal: &mut T)
+    pub fn traverse_postorder_mut<T:PostorderNodeMutTraversal>(&mut self, traversal: &mut T)
                                   -> bool {
         if traversal.should_prune(self) {
             return true
@@ -444,7 +428,7 @@ impl<'ln> ThreadSafeLayoutNode<'ln> {
         loop {
             match opt_kid {
                 None => break,
-                Some(kid) => {
+                Some(mut kid) => {
                     if !kid.traverse_postorder_mut(traversal) {
                         return false
                     }
@@ -465,8 +449,8 @@ pub struct ThreadSafeLayoutNodeChildrenIterator<'a> {
 
 impl<'a> Iterator<ThreadSafeLayoutNode<'a>> for ThreadSafeLayoutNodeChildrenIterator<'a> {
     fn next(&mut self) -> Option<ThreadSafeLayoutNode<'a>> {
-        let node = self.current_node;
-        self.current_node = self.current_node.and_then(|node| {
+        let node = self.current_node.clone();
+        self.current_node = self.current_node.clone().and_then(|node| {
             unsafe {
                 node.next_sibling()
             }
@@ -491,17 +475,19 @@ impl<'le> ThreadSafeLayoutElement<'le> {
 /// A bottom-up, parallelizable traversal.
 pub trait PostorderNodeMutTraversal {
     /// The operation to perform. Return true to continue or false to stop.
-    fn process<'a>(&'a mut self, node: ThreadSafeLayoutNode<'a>) -> bool;
+    fn process<'a>(&'a mut self, node: &ThreadSafeLayoutNode<'a>) -> bool;
 
     /// Returns true if this node should be pruned. If this returns true, we skip the operation
     /// entirely and do not process any descendant nodes. This is called *before* child nodes are
     /// visited. The default implementation never prunes any nodes.
-    fn should_prune<'a>(&'a self, _node: ThreadSafeLayoutNode<'a>) -> bool {
+    fn should_prune<'a>(&'a self, _node: &ThreadSafeLayoutNode<'a>) -> bool {
         false
     }
 }
 
-pub type UnsafeLayoutNode = (uint, uint);
+/// Opaque type stored in type-unsafe work queues for parallel layout.
+/// Must be transmutable to and from LayoutNode/ThreadsafeLayoutNode/PaddedUnsafeFlow.
+pub type UnsafeLayoutNode = (uint, uint, uint);
 
 pub fn layout_node_to_unsafe_layout_node(node: &LayoutNode) -> UnsafeLayoutNode {
     unsafe {

src/components/msg/compositor_msg.rs

@@ -11,6 +11,8 @@ use layers::platform::surface::{NativeSurface, NativeSurfaceMethods};
 
 use constellation_msg::PipelineId;
 
+use extra::serialize::{Encoder, Encodable};
+
 pub struct LayerBuffer {
     /// The native surface which can be shared between threads or processes. On Mac this is an
     /// `IOSurface`; on Linux this is an X Pixmap; on Android this is an `EGLImageKHR`.
@@ -94,6 +96,11 @@ pub trait ScriptListener : Clone {
     fn close(&self);
 }
 
+impl<S: Encoder> Encodable<S> for @ScriptListener {
+    fn encode(&self, _s: &mut S) {
+    }
+}
+
 /// The interface used by the quadtree and buffer map to get info about layer buffers.
 pub trait Tile {
     /// Returns the amount of memory used by the tile

src/components/msg/constellation_msg.rs

@@ -60,8 +60,8 @@ pub enum NavigationDirection {
     Back,
 }
 
-#[deriving(Clone, Eq, IterBytes)]
+#[deriving(Clone, Eq, IterBytes, Encodable)]
 pub struct PipelineId(uint);
 
-#[deriving(Clone, Eq, IterBytes)]
+#[deriving(Clone, Eq, IterBytes, Encodable)]
 pub struct SubpageId(uint);

src/components/msg/msg.rs

@@ -5,6 +5,8 @@
 #[crate_id = "github.com/mozilla/servo#msg:0.1"];
 #[crate_type = "lib"];
 
+#[feature(managed_boxes)];
+
 extern mod azure;
 extern mod extra;
 extern mod geom;

src/components/net/image_cache_task.rs

@@ -14,6 +14,7 @@ use std::util::replace;
 use std::result;
 use extra::arc::{Arc,MutexArc};
 use extra::url::Url;
+use extra::serialize::{Encoder, Encodable};
 
 pub enum Msg {
     /// Tell the cache that we may need a particular image soon. Must be posted
@@ -80,6 +81,11 @@ pub struct ImageCacheTask {
     chan: SharedChan<Msg>,
 }
 
+impl<S: Encoder> Encodable<S> for ImageCacheTask {
+    fn encode(&self, _: &mut S) {
+    }
+}
+
 type DecoderFactory = fn() -> proc(&[u8]) -> Option<Image>;
 
 pub fn ImageCacheTask(resource_task: ResourceTask) -> ImageCacheTask {

src/components/script/dom/attr.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::AttrBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::window::Window;
 use servo_util::namespace::{Namespace, Null};
@@ -10,6 +11,7 @@ use servo_util::str::DOMString;
 
 use std::util;
 
+#[deriving(Encodable)]
 pub struct Attr {
     reflector_: Reflector,
     local_name: DOMString,
@@ -43,22 +45,22 @@ impl Attr {
         }
     }
 
-    pub fn new(window: &Window, local_name: DOMString, value: DOMString) -> @mut Attr {
+    pub fn new(window: &Window, local_name: DOMString, value: DOMString) -> JS<Attr> {
         let name = local_name.clone();
         Attr::new_helper(window, local_name, value, name, Null, None)
     }
 
     pub fn new_ns(window: &Window, local_name: DOMString, value: DOMString,
                   name: DOMString, namespace: Namespace,
-                  prefix: Option<DOMString>) -> @mut Attr {
+                  prefix: Option<DOMString>) -> JS<Attr> {
         Attr::new_helper(window, local_name, value, name, namespace, prefix)
     }
 
     fn new_helper(window: &Window, local_name: DOMString, value: DOMString,
                   name: DOMString, namespace: Namespace,
-                  prefix: Option<DOMString>) -> @mut Attr {
+                  prefix: Option<DOMString>) -> JS<Attr> {
         let attr = Attr::new_inherited(local_name, value, name, namespace, prefix);
-        reflect_dom_object(@mut attr, window, AttrBinding::Wrap)
+        reflect_dom_object(~attr, window, AttrBinding::Wrap)
     }
 
     pub fn set_value(&mut self, mut value: DOMString) -> DOMString {

src/components/script/dom/attrlist.rs

@@ -4,18 +4,20 @@
 
 use dom::attr::Attr;
 use dom::bindings::codegen::AttrListBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
-use dom::node::{AbstractNode};
+use dom::element::Element;
 use dom::window::Window;
 
+#[deriving(Encodable)]
 pub struct AttrList {
     reflector_: Reflector,
-    window: @mut Window,
-    owner: AbstractNode,
+    window: JS<Window>,
+    owner: JS<Element>,
 }
 
 impl AttrList {
-    pub fn new_inherited(window: @mut Window, elem: AbstractNode) -> AttrList {
+    pub fn new_inherited(window: JS<Window>, elem: JS<Element>) -> AttrList {
         AttrList {
             reflector_: Reflector::new(),
             window: window,
@@ -23,22 +25,20 @@ impl AttrList {
         }
     }
 
-    pub fn new(window: @mut Window, elem: AbstractNode) -> @mut AttrList {
-        reflect_dom_object(@mut AttrList::new_inherited(window, elem),
-                           window, AttrListBinding::Wrap)
+    pub fn new(window: &JS<Window>, elem: &JS<Element>) -> JS<AttrList> {
+        reflect_dom_object(~AttrList::new_inherited(window.clone(), elem.clone()),
+                           window.get(), AttrListBinding::Wrap)
     }
 
     pub fn Length(&self) -> u32 {
-        self.owner.with_imm_element(|elem| elem.attrs.len() as u32)
+        self.owner.get().attrs.len() as u32
     }
 
-    pub fn Item(&self, index: u32) -> Option<@mut Attr> {
-        self.owner.with_imm_element(|elem| {
-            elem.attrs.get_opt(index as uint).map(|&x| x)
-        })
+    pub fn Item(&self, index: u32) -> Option<JS<Attr>> {
+        self.owner.get().attrs.get_opt(index as uint).map(|x| x.clone())
     }
 
-    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<@mut Attr> {
+    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<JS<Attr>> {
         let item = self.Item(index);
         *found = item.is_some();
         item

src/components/script/dom/bindings/callback.rs

@@ -4,12 +4,15 @@
 
 use dom::bindings::utils::Reflectable;
 use js::jsapi::{JSContext, JSObject, JS_WrapObject, JSVal, JS_ObjectIsCallable};
-use js::jsapi::JS_GetProperty;
-use js::{JSVAL_IS_OBJECT, JSVAL_TO_OBJECT};
+use js::jsapi::{JS_GetProperty, JSTracer, JS_CallTracer};
+use js::{JSVAL_IS_OBJECT, JSVAL_TO_OBJECT, JSTRACE_OBJECT};
 
+use std::cast;
 use std::libc;
 use std::ptr;
 
+use extra::serialize::{Encodable, Encoder};
+
 pub enum ExceptionHandling {
     // Report any exception and don't throw it to the caller code.
     eReportExceptions,
@@ -26,6 +29,20 @@ pub struct CallbackInterface {
     callback: *JSObject
 }
 
+impl<S: Encoder> Encodable<S> for CallbackInterface {
+    fn encode(&self, s: &mut S) {
+        unsafe {
+            let tracer: *mut JSTracer = cast::transmute(s);
+            "callback".to_c_str().with_ref(|name| {
+                (*tracer).debugPrinter = ptr::null();
+                (*tracer).debugPrintIndex = -1;
+                (*tracer).debugPrintArg = name as *libc::c_void;
+                JS_CallTracer(tracer as *JSTracer, self.callback, JSTRACE_OBJECT as u32);
+            });
+        }
+    }
+}
+
 pub trait CallbackContainer {
     fn callback(&self) -> *JSObject;
 }
@@ -66,7 +83,7 @@ pub fn GetJSObjectFromCallback<T: CallbackContainer>(callback: &T) -> *JSObject
 
 pub fn WrapCallThisObject<T: 'static + CallbackContainer + Reflectable>(cx: *JSContext,
                                                                         _scope: *JSObject,
-                                                                        p: @mut T) -> *JSObject {
+                                                                        p: ~T) -> *JSObject {
     let obj = GetJSObjectFromCallback(p);
     assert!(obj.is_not_null());
 

src/components/script/dom/bindings/codegen/Bindings.conf

@@ -96,7 +96,6 @@ DOMInterfaces = {
 
 'Blob': [
 {
-    'headerFile': 'nsIDOMFile.h',
 },
 #{
 #    'workers': True,
@@ -121,19 +120,14 @@ DOMInterfaces = {
 }],
 
 'CharacterData': {
-    'nativeType': 'AbstractNode',
-    'concreteType': 'CharacterData',
-    'pointerType': ''
 },
 
 'ClientRect': [
 {
-    'nativeType': 'ClientRect',
 }],
 
 'ClientRectList': [
 {
-    'nativeType': 'ClientRectList',
 }],
 
 'Console': {
@@ -150,8 +144,6 @@ DOMInterfaces = {
 },
 
 'Document': {
-    'nativeType': 'AbstractDocument',
-    'pointerType': '',
     'customTrace': 'trace',
     'needsAbstract': [
         'createComment',
@@ -165,15 +157,12 @@ DOMInterfaces = {
 },
 
 'DOMException': {
-    'nativeType': 'DOMException',
 },
 
 'DOMImplementation': {
-    'nativeType': 'DOMImplementation',
 },
 
 'DOMParser': {
-    'nativeType': 'DOMParser',
 },
 
 'DOMSettableTokenList': [
@@ -195,15 +184,10 @@ DOMInterfaces = {
 }],
 
 'Element': {
-    'nativeType': 'AbstractNode',
-    'pointerType': '',
     'needsAbstract': ['getClientRects', 'getBoundingClientRect', 'setAttribute', 'setAttributeNS', 'removeAttribute', 'removeAttributeNS', 'id', 'attributes', 'innerHTML', 'outerHTML']
 },
 
 'Event': {
-    'nativeType': 'AbstractEvent',
-    'concreteType': 'Event',
-    'pointerType': '',
 },
 
 'EventListener': {
@@ -211,9 +195,6 @@ DOMInterfaces = {
 },
 
 'EventTarget': {
-    'nativeType': 'AbstractEventTarget',
-    'concreteType': 'EventTarget',
-    'pointerType': '',
     'needsAbstract': ['dispatchEvent']
 },
 
@@ -241,22 +222,12 @@ DOMInterfaces = {
 
 'HTMLCollection': [
 {
-    'nativeType': 'HTMLCollection',
-    'pointerType': '@mut '
 }],
 
 'HTMLDocument': {
-    'nativeType': 'AbstractDocument',
-    'pointerType': '',
     'customTrace': 'trace'
 },
 
-'HTMLFormElement': {
-    'nativeType': 'AbstractNode',
-    'pointerType': '',
-    'register': False
-},
-
 'HTMLOptionsCollection': [
 {
     'nativeType': 'nsHTMLOptionCollection',
@@ -306,27 +277,21 @@ DOMInterfaces = {
 }],
 
 'MouseEvent': {
-    'nativeType': 'AbstractEvent',
-    'concreteType': 'MouseEvent',
-    'pointerType': '',
 },
 
 'Navigator': {
 },
 
 'Node': {
-    'nativeType': 'AbstractNode',
-    'concreteType': 'Node',
-    'pointerType': '',
     'needsAbstract': [
         'appendChild',
+        'childNodes',
 	'insertBefore',
-        'replaceChild',
         'nodeName',
         'nodeValue',
         'removeChild',
+        'replaceChild',
         'textContent',
-        'childNodes',
         'contains',
         'isEqualNode',
     ]
@@ -334,8 +299,6 @@ DOMInterfaces = {
 
 'NodeList': [
 {
-    'nativeType': 'NodeList',
-    'pointerType': '@mut ',
     'resultNotAddRefed': ['item']
 }],
 
@@ -410,9 +373,6 @@ DOMInterfaces = {
 }],
 
 'UIEvent': {
-    'nativeType': 'AbstractEvent',
-    'concreteType': 'UIEvent',
-    'pointerType': '',
 },
 
 'ValidityState': {
@@ -592,7 +552,7 @@ def addExternalIface(iface, nativeType=None, headerFile=None, pointerType=None):
 # FIXME: This should be renamed: https://github.com/mozilla/servo/issues/1625
 def addHTMLElement(element, concrete=None, needsAbstract=[]):
   DOMInterfaces[element] = {
-    'nativeType': 'AbstractNode',
+    'nativeType': 'JS<%s>' % element,
     'pointerType': '',
     'concreteType': concrete if concrete else element,
     'customTrace': 'trace',

src/components/script/dom/bindings/codegen/CodegenRust.py

@@ -102,7 +102,8 @@ class CastableObjectUnwrapper():
                               "source" : source,
                               "target" : target,
                               "codeOnFailure" : CGIndenter(CGGeneric(codeOnFailure), 4).define(),
-                              "unwrapped_val" : "Some(val)" if isOptional else "val" }
+                              "unwrapped_val" : "Some(val)" if isOptional else "val",
+                              "unwrapFn": "unwrap_jsmanaged" if 'JS' in descriptor.nativeType else "unwrap_object"}
         if descriptor.hasXPConnectImpls:
             # We don't use xpc_qsUnwrapThis because it will always throw on
             # unwrap failure, whereas we want to control whether we throw or
@@ -123,7 +124,7 @@ class CastableObjectUnwrapper():
 
     def __str__(self):
         return string.Template(
-"""match unwrap_object(${source}, ${prototype}, ${depth}) {
+"""match ${unwrapFn}(${source}, ${prototype}, ${depth}) {
   Ok(val) => ${target} = ${unwrapped_val},
   Err(()) => {
     ${codeOnFailure}
@@ -406,8 +407,7 @@ class FakeCastableDescriptor():
     def __init__(self, descriptor):
         self.castable = True
         self.workers = descriptor.workers
-        self.nativeType = descriptor.nativeType
-        self.pointerType = descriptor.pointerType
+        self.nativeType = "*Box<%s>" % descriptor.concreteType
         self.name = descriptor.name
         self.hasXPConnectImpls = descriptor.hasXPConnectImpls
         class FakeInterface:
@@ -934,8 +934,7 @@ for (uint32_t i = 0; i < length; ++i) {
         forceOwningType = (descriptor.interface.isCallback() and
                            not descriptor.workers) or isMember
 
-        typeName = descriptor.nativeType
-        typePtr = descriptor.pointerType + typeName
+        typePtr = descriptor.nativeType
 
         # Compute a few things:
         #  - declType is the type we want to return as the first element of our
@@ -1730,9 +1729,7 @@ def getRetvalDeclarationForType(returnType, descriptorProvider,
             returnType.unroll().inner.identifier.name)
         result = CGGeneric(descriptor.nativeType)
         if returnType.nullable():
-            result = CGWrapper(result, pre=("Option<" + descriptor.pointerType), post=">")
-        else:
-            result = CGWrapper(result, pre=descriptor.pointerType)
+            result = CGWrapper(result, pre="Option<", post=">")
         return result, False
     if returnType.isCallback():
         # XXXbz we're going to assume that callback types are always
@@ -2497,33 +2494,40 @@ class CGAbstractMethod(CGThing):
     def definition_body(self):
         assert(False) # Override me!
 
+def DOMObjectPointerType(descriptor):
+    return "~"
+
+def DOMObjectPointerArg(descriptor):
+    return DOMObjectPointerType(descriptor) + descriptor.concreteType
+
 def CreateBindingJSObject(descriptor, parent=None):
+    create = "  let raw: *mut %s = &mut *aObject;\n" % descriptor.concreteType;
     if descriptor.proxy:
         assert not descriptor.createGlobal
         handler = """
   let page = page_from_context(aCx);
   let handler = (*page).js_info.get_ref().dom_static.proxy_handlers.get(&(PrototypeList::id::%s as uint));
 """ % descriptor.name
-        create = handler + """  let obj = NewProxyObject(aCx, *handler,
-                           ptr::to_unsafe_ptr(&RUST_PRIVATE_TO_JSVAL(squirrel_away(aObject) as *libc::c_void)),
+        create += handler + """  let obj = NewProxyObject(aCx, *handler,
+                           ptr::to_unsafe_ptr(&RUST_PRIVATE_TO_JSVAL(squirrel_away_unique(aObject) as *libc::c_void)),
                            proto, %s,
                            ptr::null(), ptr::null());
   if obj.is_null() {
     return ptr::null();
   }
 
-""" % parent
+""" % (parent)
     else:
         if descriptor.createGlobal:
-            create = "  let obj = CreateDOMGlobal(aCx, &Class.base);\n"
+            create += "  let obj = CreateDOMGlobal(aCx, &Class.base);\n"
         else:
-            create = "  let obj = JS_NewObject(aCx, &Class.base, proto, %s);\n" % parent
+            create += "  let obj = JS_NewObject(aCx, &Class.base, proto, %s);\n" % parent
         create += """  if obj.is_null() {
     return ptr::null();
   }
 
   JS_SetReservedSlot(obj, DOM_OBJECT_SLOT as u32,
-                     RUST_PRIVATE_TO_JSVAL(squirrel_away(aObject) as *libc::c_void));
+                     RUST_PRIVATE_TO_JSVAL(squirrel_away_unique(aObject) as *libc::c_void));
 """
     return create
 
@@ -2531,7 +2535,7 @@ class CGWrapWithCacheMethod(CGAbstractMethod):
     def __init__(self, descriptor):
         assert descriptor.interface.hasInterfacePrototypeObject()
         args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aScope'),
-                Argument('@mut ' + descriptor.concreteType, 'aObject')]
+                Argument(DOMObjectPointerArg(descriptor), 'aObject', mutable=True)]
         CGAbstractMethod.__init__(self, descriptor, 'Wrap_', '*JSObject', args)
 
     def definition_body(self):
@@ -2548,20 +2552,20 @@ class CGWrapWithCacheMethod(CGAbstractMethod):
   if proto.is_null() {
     return ptr::null();
   }
+
 %s
 
-  //NS_ADDREF(aObject);
+  (*raw).mut_reflector().set_jsobject(obj);
 
-  aObject.mut_reflector().set_jsobject(obj);
-
-  return obj;""" % (CreateBindingJSObject(self.descriptor, "aScope"))
+  return obj;""" % CreateBindingJSObject(self.descriptor, "aScope")
         else:
             return """
   assert!(aScope.is_null());
+
 %s
   let proto = GetProtoObject(aCx, obj, obj);
   JS_SetPrototype(aCx, obj, proto);
-  aObject.mut_reflector().set_jsobject(obj);
+  (*raw).mut_reflector().set_jsobject(obj);
   return obj;""" % CreateBindingJSObject(self.descriptor)
 
 class CGWrapMethod(CGAbstractMethod):
@@ -2569,7 +2573,7 @@ class CGWrapMethod(CGAbstractMethod):
         # XXX can we wrap if we don't have an interface prototype object?
         assert descriptor.interface.hasInterfacePrototypeObject()
         args = [Argument('*JSContext', 'aCx'), Argument('*JSObject', 'aScope'),
-                Argument('@mut ' + descriptor.concreteType, 'aObject')]
+                Argument(DOMObjectPointerArg(descriptor), 'aObject', mutable=True)]
         CGAbstractMethod.__init__(self, descriptor, 'Wrap', '*JSObject', args, inline=True, pub=True)
 
     def definition_body(self):
@@ -2961,7 +2965,11 @@ class CGCallGenerator(CGThing):
             if a.type.isObject() and not a.type.nullable() and not a.optional:
                 name = "(JSObject&)" + name
             #XXXjdm Perhaps we should pass all nontrivial types by borrowed pointer
-            if a.type.isDictionary():
+            if a.type.isGeckoInterface():
+                argDescriptor = descriptorProvider.getDescriptor(a.type.name)
+                if not (a.type.nullable() or a.optional):
+                    name = "&mut " + name
+            elif a.type.isDictionary():
                 name = "&" + name
             args.append(CGGeneric(name))
 
@@ -3288,8 +3296,8 @@ class CGSpecializedMethod(CGAbstractExternMethod):
         argsPre = []
         if name in self.descriptor.needsAbstract:
             abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
-            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
-            argsPre = ['abstract_this']
+            extraPre = '  let mut abstract_this = %s::from_box(this);\n' % abstractName
+            argsPre = ['&mut abstract_this']
         return CGWrapper(CGMethodCall(argsPre, nativeName, self.method.isStatic(),
                                       self.descriptor, self.method),
                          pre=extraPre +
@@ -3317,8 +3325,10 @@ class CGGenericGetter(CGAbstractBindingMethod):
 
     def generate_code(self):
         return CGIndenter(CGGeneric(
-            "let info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, &*vp));\n"
-            "return CallJitPropertyOp(info, cx, obj, this as *libc::c_void, &*vp);"))
+            "return with_gc_disabled(cx, || {\n"
+            "  let info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, &*vp));\n"
+            "  CallJitPropertyOp(info, cx, obj, this as *libc::c_void, &*vp)\n"
+            "});\n"))
 
 class CGSpecializedGetter(CGAbstractExternMethod):
     """
@@ -3348,8 +3358,8 @@ class CGSpecializedGetter(CGAbstractExternMethod):
                                                             getter=True))
         if name in self.descriptor.needsAbstract:
             abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
-            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
-            argsPre = ['abstract_this']
+            extraPre = '  let mut abstract_this = %s::from_box(this);\n' % abstractName
+            argsPre = ['&mut abstract_this']
         if resultOutParam or self.attr.type.nullable() or not infallible:
             nativeName = "Get" + nativeName
         return CGWrapper(CGIndenter(CGGetterCall(argsPre, self.attr.type, nativeName,
@@ -3381,7 +3391,10 @@ class CGGenericSetter(CGAbstractBindingMethod):
                 "let undef = JSVAL_VOID;\n"
                 "let argv: *JSVal = if argc != 0 { JS_ARGV(cx, cast::transmute(vp)) } else { &undef as *JSVal };\n"
                 "let info: *JSJitInfo = RUST_FUNCTION_VALUE_TO_JITINFO(JS_CALLEE(cx, cast::transmute(vp)));\n"
-                "if CallJitPropertyOp(info, cx, obj, this as *libc::c_void, argv) == 0 {"
+                "let ok = with_gc_disabled(cx, || {\n"
+                "  CallJitPropertyOp(info, cx, obj, this as *libc::c_void, argv)\n"
+                "});\n"
+                "if ok == 0 {\n"
                 "  return 0;\n"
                 "}\n"
                 "*vp = JSVAL_VOID;\n"
@@ -3408,8 +3421,8 @@ class CGSpecializedSetter(CGAbstractExternMethod):
         extraPre = ''
         if name in self.descriptor.needsAbstract:
             abstractName = re.sub(r'<\w+>', '', self.descriptor.nativeType)
-            extraPre = '  let abstract_this = %s::from_box(this);\n' % abstractName
-            argsPre = ['abstract_this']
+            extraPre = '  let mut abstract_this = %s::from_box(this);\n' % abstractName
+            argsPre = ['&mut abstract_this']
         return CGWrapper(CGIndenter(CGSetterCall(argsPre, self.attr.type, nativeName,
                                                  self.descriptor, self.attr)),
                          pre=extraPre +
@@ -4482,9 +4495,9 @@ def finalizeHook(descriptor, hookName, context):
     else:
         assert descriptor.nativeIsISupports
         release = """let val = JS_GetReservedSlot(obj, dom_object_slot(obj));
-let _: @mut %s = cast::transmute(RUST_JSVAL_TO_PRIVATE(val));
+let _: %s %s = cast::transmute(RUST_JSVAL_TO_PRIVATE(val));
 debug!("%s finalize: {:p}", this);
-""" % (descriptor.concreteType, descriptor.concreteType)
+""" % (DOMObjectPointerType(descriptor), descriptor.concreteType, descriptor.concreteType)
     #return clearWrapper + release
     return release
 
@@ -4530,10 +4543,10 @@ class CGClassConstructHook(CGAbstractExternMethod):
   //       or through unwrapping a slot or something). We'll punt and get the Window
   //       from the context for now. 
   let page = page_from_context(cx);
-  let global = (*page).frame.get_ref().window;
+  let global = (*page).frame.get_ref().window.clone();
   let obj = global.reflector().get_jsobject();
 """
-            preArgs = ["global"]
+            preArgs = ["&global"]
 
         name = self._ctor.identifier.name
         nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
@@ -5151,6 +5164,7 @@ class CGBindingRoot(CGThing):
                           'js::jsfriendapi::bindgen::*',
                           'js::glue::*',
                           'dom::types::*',
+                          'dom::bindings::js::JS',
                           'dom::bindings::utils::*',
                           'dom::bindings::callback::*',
                           'dom::bindings::conversions::*',
@@ -5158,10 +5172,6 @@ class CGBindingRoot(CGThing):
                           'script_task::{JSPageInfo, page_from_context}',
                           'dom::bindings::proxyhandler',
                           'dom::bindings::proxyhandler::*',
-                          'dom::document::AbstractDocument',
-                          'dom::node::AbstractNode',
-                          'dom::eventtarget::AbstractEventTarget',
-                          'dom::event::AbstractEvent',
                           'servo_util::str::DOMString',
                           'servo_util::vec::zip_copies',
                           'std::cast',
@@ -5427,9 +5437,9 @@ class CGNativeMember(ClassMethod):
                     else:
                         typeDecl = "NonNull<%s>"
                 else:
-                    typeDecl = "%s%s"
+                    typeDecl = "%s"
             descriptor = self.descriptorProvider.getDescriptor(iface.identifier.name)
-            return (typeDecl % (descriptor.pointerType, descriptor.nativeType),
+            return (typeDecl % descriptor.nativeType,
                     False, False)
 
         if type.isSpiderMonkeyInterface():
@@ -5560,7 +5570,7 @@ class CGCallback(CGClass):
                          bases=[ClassBase(baseName)],
                          constructors=self.getConstructors(),
                          methods=realMethods+getters+setters,
-                         decorators="#[deriving(Eq,Clone)]")
+                         decorators="#[deriving(Eq,Clone,Encodable)]")
 
     def getConstructors(self):
         return [ClassConstructor(
@@ -5591,20 +5601,19 @@ class CGCallback(CGClass):
         args.append(Argument("ExceptionHandling", "aExceptionHandling",
                              "eReportExceptions"))
 
-        # Ensure the first argument is mutable
-        args[0] = Argument(args[0].argType, args[0].name, args[0].default, mutable=True)
+        args[0] = Argument('&' + args[0].argType, args[0].name, args[0].default)
         method.args[2] = args[0]
 
         # And now insert our template argument.
         argsWithoutThis = list(args)
-        args.insert(0, Argument("@mut T",  "thisObj"))
+        args.insert(0, Argument("~T",  "thisObj"))
 
         # And the self argument
         method.args.insert(0, Argument(None, "&self"))
         args.insert(0, Argument(None, "&self"))
         argsWithoutThis.insert(0, Argument(None, "&self"))
 
-        setupCall = ("let s = CallSetup::new(cx_for_dom_object(&mut ${cxProvider}), aExceptionHandling);\n"
+        setupCall = ("let s = CallSetup::new(cx_for_dom_object(${cxProvider}), aExceptionHandling);\n"
                      "if s.GetContext().is_null() {\n"
                      "  return${errorReturn};\n"
                      "}\n")
@@ -5619,7 +5628,7 @@ class CGCallback(CGClass):
                 "errorReturn" : method.getDefaultRetval(),
                 "callArgs" : ", ".join(argnamesWithThis),
                 "methodName": 'self.' + method.name,
-                "cxProvider": '*thisObj'
+                "cxProvider": 'thisObj'
                 })
         bodyWithoutThis = string.Template(
             setupCall +
@@ -5954,8 +5963,14 @@ class CallbackMethod(CallbackMember):
             replacements["argv"] = "nullptr"
             replacements["argc"] = "0"
         return string.Template("${getCallable}"
-                "if unsafe { JS_CallFunctionValue(cx, ${thisObj}, callable,\n"
-                "                        ${argc}, ${argv}, &rval) == 0 } {\n"
+                "let ok = unsafe {\n"
+                "  //JS_AllowGC(cx); // It's unsafe to enable GC at arbitrary points during Rust execution; leave it disabled\n"
+                "  let ok = JS_CallFunctionValue(cx, ${thisObj}, callable,\n"
+                "                                ${argc}, ${argv}, &rval);\n"
+                "  //JS_InhibitGC(cx);\n"
+                "  ok\n"
+                "};\n"
+                "if ok == 0 {\n"
                 "  return${errorReturn};\n"
                 "}\n").substitute(replacements)
 
@@ -6176,3 +6191,66 @@ class GlobalGenRoots():
         curr = CGList([CGGeneric(declare="pub mod %sBinding;\n" % name) for name in descriptors])
         curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
         return curr
+
+    @staticmethod
+    def InheritTypes(config):
+
+        descriptors = config.getDescriptors(register=True, hasInterfaceObject=True)
+        allprotos = [CGGeneric(declare="#[allow(unused_imports)];\n"),
+                     CGGeneric(declare="use dom::types::*;\n"),
+                     CGGeneric(declare="use dom::bindings::js::JS;\n"),
+                     CGGeneric(declare="use dom::bindings::utils::Traceable;\n"),
+                     CGGeneric(declare="use extra::serialize::{Encodable, Encoder};\n"),
+                     CGGeneric(declare="use js::jsapi::JSTracer;\n\n")]
+        for descriptor in descriptors:
+            name = descriptor.name
+            protos = [CGGeneric(declare='pub trait %s {}\n' % (name + 'Base'))]
+            for proto in descriptor.prototypeChain:
+                protos += [CGGeneric(declare='impl %s for %s {}\n' % (proto + 'Base',
+                                                                      descriptor.concreteType))]
+            derived = [CGGeneric(declare='pub trait %s { fn %s(&self) -> bool; }\n' %
+                                 (name + 'Derived', 'is_' + name.lower()))]
+            for protoName in descriptor.prototypeChain[1:-1]:
+                protoDescriptor = config.getDescriptor(protoName, False)
+                delegate = string.Template('''impl ${selfName} for ${baseName} {
+  fn ${fname}(&self) -> bool {
+    self.${parentName}.${fname}()
+  }
+}
+''').substitute({'fname': 'is_' + name.lower(),
+                 'selfName': name + 'Derived',
+                 'baseName': protoDescriptor.concreteType,
+                 'parentName': protoDescriptor.prototypeChain[-2].lower()})
+                derived += [CGGeneric(declare=delegate)]
+            derived += [CGGeneric(declare='\n')]
+
+            cast = [CGGeneric(declare=string.Template('''pub trait ${castTraitName} {
+  fn from<T: ${fromBound}>(derived: &JS<T>) -> JS<Self> {
+    unsafe { derived.clone().transmute() }
+  }
+
+  fn to<T: ${toBound}>(base: &JS<T>) -> JS<Self> {
+    assert!(base.get().${checkFn}());
+    unsafe { base.clone().transmute() }
+  }
+}
+''').substitute({'checkFn': 'is_' + name.lower(),
+                 'castTraitName': name + 'Cast',
+                 'fromBound': name + 'Base',
+                 'toBound': name + 'Derived'})),
+                    CGGeneric(declare="impl %s for %s {}\n\n" % (name + 'Cast', name))]
+
+            trace = [CGGeneric(declare=string.Template('''impl Traceable for ${name} {
+    fn trace(&self, tracer: *mut JSTracer) {
+        unsafe {
+            self.encode(&mut *tracer);
+        }
+    }
+}
+''').substitute({'name': name}))]
+
+            allprotos += protos + derived + cast + trace
+
+        curr = CGList(allprotos)
+        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
+        return curr

src/components/script/dom/bindings/codegen/Configuration.py

@@ -158,10 +158,9 @@ class Descriptor(DescriptorProvider):
             if self.workers:
                 nativeTypeDefault = "workers::" + ifaceName
             else:
-                nativeTypeDefault = ifaceName
+                nativeTypeDefault = 'JS<%s>' % ifaceName
 
         self.nativeType = desc.get('nativeType', nativeTypeDefault)
-        self.pointerType = desc.get('pointerType', '@mut ')
         self.concreteType = desc.get('concreteType', ifaceName)
         self.needsAbstract = desc.get('needsAbstract', [])
         self.hasInstanceInterface = desc.get('hasInstanceInterface', None)
@@ -253,7 +252,7 @@ class Descriptor(DescriptorProvider):
         self.prefable = desc.get('prefable', False)
 
         self.nativeIsISupports = not self.workers
-        self.customTrace = desc.get('customTrace', self.workers)
+        self.customTrace = desc.get('customTrace', self.workers) or 'trace'
         self.customFinalize = desc.get('customFinalize', self.workers)
         self.wrapperCache = self.workers or desc.get('wrapperCache', True)
 

src/components/script/dom/bindings/codegen/GlobalGen.py

@@ -83,6 +83,9 @@ def main():
     # Generate the type list.
     generate_file(config, 'InterfaceTypes', 'declare+define')
 
+    # Generate the type list.
+    generate_file(config, 'InheritTypes', 'declare+define')
+
     # Generate the module declarations.
     generate_file(config, 'BindingDeclarations', 'declare+define')
 

src/components/script/dom/bindings/element.rs

@@ -3,9 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::types::*;
-use dom::bindings::utils::{Reflectable, Reflector, Traceable};
-
-use js::jsapi::JSTracer;
+use dom::bindings::utils::{Reflectable, Reflector};
 
 // generate_cacheable_wrapper
 macro_rules! generate_cacheable_wrapper(
@@ -58,277 +56,149 @@ macro_rules! generate_cacheable_wrapper_base(
     )
 )
 
-
-// generate_traceable
-macro_rules! generate_traceable(
-    ($name: path) => (
-        generate_traceable_base!($name, element)
-    )
-)
-
-macro_rules! generate_traceable_characterdata(
-    ($name: path) => (
-        generate_traceable_base!($name, characterdata)
-    )
-)
-
-macro_rules! generate_traceable_htmlelement(
-    ($name: path) => (
-        generate_traceable_base!($name, htmlelement)
-    )
-)
-
-macro_rules! generate_traceable_htmlmediaelement(
-    ($name: path) => (
-        generate_traceable_base!($name, htmlmediaelement)
-    )
-)
-
-macro_rules! generate_traceable_htmltablecellelement(
-    ($name: path) => (
-        generate_traceable_base!($name, htmltablecellelement)
-    )
-)
-
-macro_rules! generate_traceable_node(
-    ($name: path) => (
-        generate_traceable_base!($name, node)
-    )
-)
-
-macro_rules! generate_traceable_base(
-    ($name: path, $parent: ident) => (
-        impl Traceable for $name {
-            fn trace(&self, trc: *mut JSTracer) {
-                self.$parent.trace(trc);
-            }
-        }
-    )
-)
-
-
 generate_cacheable_wrapper_characterdata!(Comment, CommentBinding::Wrap)
-generate_traceable_characterdata!(Comment)
 
 generate_cacheable_wrapper_node!(DocumentFragment, DocumentFragmentBinding::Wrap)
-generate_traceable_node!(DocumentFragment)
 
 generate_cacheable_wrapper_node!(DocumentType, DocumentTypeBinding::Wrap)
-generate_traceable_node!(DocumentType)
 
 generate_cacheable_wrapper_characterdata!(Text, TextBinding::Wrap)
-generate_traceable_characterdata!(Text)
 
 generate_cacheable_wrapper_characterdata!(ProcessingInstruction, ProcessingInstruction::Wrap)
-generate_traceable_characterdata!(ProcessingInstruction)
 
 generate_cacheable_wrapper_htmlelement!(HTMLHeadElement, HTMLHeadElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLHeadElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLAnchorElement, HTMLAnchorElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLAnchorElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLAppletElement, HTMLAppletElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLAppletElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLAreaElement, HTMLAreaElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLAreaElement)
 
 generate_cacheable_wrapper_htmlmediaelement!(HTMLAudioElement, HTMLAudioElementBinding::Wrap)
-generate_traceable_htmlmediaelement!(HTMLAudioElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLBaseElement, HTMLBaseElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLBaseElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLBodyElement, HTMLBodyElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLBodyElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLButtonElement, HTMLButtonElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLButtonElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLCanvasElement, HTMLCanvasElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLCanvasElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLDataListElement, HTMLDataListElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLDataListElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLDListElement, HTMLDListElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLDListElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLFormElement, HTMLFormElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLFormElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLFrameElement, HTMLFrameElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLFrameElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLFrameSetElement, HTMLFrameSetElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLFrameSetElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLBRElement, HTMLBRElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLBRElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLHRElement, HTMLHRElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLHRElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLHtmlElement, HTMLHtmlElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLHtmlElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLDataElement, HTMLDataElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLDataElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLDirectoryElement, HTMLDirectoryElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLDirectoryElement)
-
 generate_cacheable_wrapper_htmlelement!(HTMLDivElement, HTMLDivElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLDivElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLEmbedElement, HTMLEmbedElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLEmbedElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLFieldSetElement, HTMLFieldSetElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLFieldSetElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLFontElement, HTMLFontElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLFontElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLHeadingElement, HTMLHeadingElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLHeadingElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLIFrameElement, HTMLIFrameElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLIFrameElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLImageElement, HTMLImageElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLImageElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLInputElement, HTMLInputElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLInputElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLLabelElement, HTMLLabelElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLLabelElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLLegendElement, HTMLLegendElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLLegendElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLLIElement, HTMLLIElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLLIElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLLinkElement, HTMLLinkElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLLinkElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLMainElement, HTMLMainElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLMainElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLMapElement, HTMLMapElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLMapElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLMediaElement, HTMLMediaElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLMediaElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLMetaElement, HTMLMetaElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLMetaElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLMeterElement, HTMLMeterElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLMeterElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLModElement, HTMLModElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLModElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLObjectElement, HTMLObjectElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLObjectElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLOListElement, HTMLOListElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLOListElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLOptGroupElement, HTMLOptGroupElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLOptGroupElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLOptionElement, HTMLOptionElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLOptionElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLOutputElement, HTMLOutputElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLOutputElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLParagraphElement, HTMLParagraphElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLParagraphElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLParamElement, HTMLParamElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLParamElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLPreElement, HTMLPreElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLPreElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLProgressElement, HTMLProgressElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLProgressElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLQuoteElement, HTMLQuoteElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLQuoteElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLScriptElement, HTMLScriptElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLScriptElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLSelectElement, HTMLSelectElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLSelectElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLSourceElement, HTMLSourceElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLSourceElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLSpanElement, HTMLSpanElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLSpanElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLStyleElement, HTMLStyleElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLStyleElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableElement, HTMLTableElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableCaptionElement, HTMLTableCaptionElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableCaptionElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableCellElement, HTMLTableCellElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableCellElement)
 
 generate_cacheable_wrapper_htmltablecellelement!(HTMLTableDataCellElement, HTMLTableDataCellElementBinding::Wrap)
-generate_traceable_htmltablecellelement!(HTMLTableDataCellElement)
 
 generate_cacheable_wrapper_htmltablecellelement!(HTMLTableHeaderCellElement, HTMLTableHeaderCellElementBinding::Wrap)
-generate_traceable_htmltablecellelement!(HTMLTableHeaderCellElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableColElement, HTMLTableColElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableColElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableRowElement, HTMLTableRowElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableRowElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTableSectionElement, HTMLTableSectionElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTableSectionElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTemplateElement, HTMLTemplateElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTemplateElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTextAreaElement, HTMLTextAreaElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTextAreaElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTitleElement, HTMLTitleElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTitleElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTimeElement, HTMLTimeElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTimeElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLTrackElement, HTMLTrackElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLTrackElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLUListElement, HTMLUListElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLUListElement)
 
 generate_cacheable_wrapper_htmlelement!(HTMLUnknownElement, HTMLUnknownElementBinding::Wrap)
-generate_traceable_htmlelement!(HTMLUnknownElement)
 
 generate_cacheable_wrapper_htmlmediaelement!(HTMLVideoElement, HTMLVideoElementBinding::Wrap)
-generate_traceable_htmlmediaelement!(HTMLVideoElement)
 
 generate_cacheable_wrapper!(HTMLElement, HTMLElementBinding::Wrap)
-generate_traceable!(HTMLElement)
-
-generate_traceable_node!(Element)
-
-generate_traceable_node!(CharacterData)

src/components/script/dom/bindings/js.rs

@@ -0,0 +1,99 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::utils::{Reflector, Reflectable};
+use dom::window;
+use js::jsapi::{JSContext, JSObject};
+use layout_interface::TrustedNodeAddress;
+
+use std::cast;
+use std::cell::RefCell;
+use std::unstable::raw::Box;
+
+pub struct JS<T> {
+    priv ptr: RefCell<*mut T>
+}
+
+impl<T> Eq for JS<T> {
+    fn eq(&self, other: &JS<T>) -> bool {
+        self.ptr == other.ptr
+    }
+}
+
+impl <T> Clone for JS<T> {
+    fn clone(&self) -> JS<T> {
+        JS {
+            ptr: self.ptr.clone()
+        }
+    }
+}
+
+impl<T: Reflectable> JS<T> {
+    pub fn new(mut obj: ~T,
+               window:  &window::Window,
+               wrap_fn: extern "Rust" fn(*JSContext, *JSObject, ~T) -> *JSObject) -> JS<T> {
+        let cx = window.get_cx();
+        let scope = window.reflector().get_jsobject();
+        let raw: *mut T = &mut *obj;
+        if wrap_fn(cx, scope, obj).is_null() {
+            fail!("Could not eagerly wrap object");
+        }
+        JS {
+            ptr: RefCell::new(raw)
+        }
+    }
+
+    pub unsafe fn from_raw(raw: *mut T) -> JS<T> {
+        JS {
+            ptr: RefCell::new(raw)
+        }
+    }
+
+
+    pub unsafe fn from_box(box_: *mut Box<T>) -> JS<T> {
+        let raw: *mut T = &mut (*box_).data;
+        JS {
+            ptr: RefCell::new(raw)
+        }
+    }
+
+    pub unsafe fn from_trusted_node_address(inner: TrustedNodeAddress) -> JS<T> {
+        JS {
+            ptr: RefCell::new(inner as *mut T)
+        }
+    }
+}
+
+impl<T: Reflectable> Reflectable for JS<T> {
+    fn reflector<'a>(&'a self) -> &'a Reflector {
+        self.get().reflector()
+    }
+
+    fn mut_reflector<'a>(&'a mut self) -> &'a mut Reflector {
+        self.get_mut().mut_reflector()
+    }
+}
+
+impl<T> JS<T> {
+    pub fn get<'a>(&'a self) -> &'a T {
+        let borrowed = self.ptr.borrow();
+        unsafe {
+            &(**borrowed.get())
+        }
+    }
+
+    pub fn get_mut<'a>(&'a mut self) -> &'a mut T {
+        let mut borrowed = self.ptr.borrow_mut();
+        unsafe {
+            &mut (**borrowed.get())
+        }
+    }
+}
+
+impl<From, To> JS<From> {
+    //XXXjdm It would be lovely if this could be private.
+    pub unsafe fn transmute(self) -> JS<To> {
+        cast::transmute(self)
+    }
+}

src/components/script/dom/bindings/node.rs

@@ -1,52 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-use dom::bindings::utils::{Reflectable, Reflector, Traceable, trace_reflector};
-use dom::types::*;
-use dom::node::AbstractNode;
-
-use std::cast;
-use std::libc;
-use std::ptr;
-use js::jsapi::{JSTracer, JSTRACE_OBJECT, JS_CallTracer};
-
-impl Reflectable for AbstractNode {
-    fn reflector<'a>(&'a self) -> &'a Reflector {
-        self.node().reflector()
-    }
-
-    fn mut_reflector<'a>(&'a mut self) -> &'a mut Reflector {
-        self.mut_node().mut_reflector()
-    }
-}
-
-impl Traceable for Node {
-    fn trace(&self, tracer: *mut JSTracer) {
-        fn trace_node(tracer: *mut JSTracer, node: Option<AbstractNode>, name: &str) {
-            if node.is_none() {
-                return;
-            }
-            debug!("tracing {:s}", name);
-            let node = node.unwrap();
-            let obj = node.reflector().get_jsobject();
-            assert!(obj.is_not_null());
-            unsafe {
-                (*tracer).debugPrinter = ptr::null();
-                (*tracer).debugPrintIndex = -1;
-                name.to_c_str().with_ref(|name| {
-                    (*tracer).debugPrintArg = name as *libc::c_void;
-                    JS_CallTracer(cast::transmute(tracer), obj, JSTRACE_OBJECT as u32);
-                });
-            }
-        }
-        debug!("tracing {:p}?:", self.reflector().get_jsobject());
-        trace_node(tracer, self.parent_node, "parent");
-        trace_node(tracer, self.first_child, "first child");
-        trace_node(tracer, self.last_child, "last child");
-        trace_node(tracer, self.next_sibling, "next sibling");
-        trace_node(tracer, self.prev_sibling, "prev sibling");
-        let owner_doc = self.owner_doc();
-        trace_reflector(tracer, "document", owner_doc.reflector());
-    }
-}

src/components/script/dom/bindings/trace.rs

@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::js::JS;
+use dom::bindings::utils::{Reflectable, trace_reflector, Reflector};
+
+use js::jsapi::JSTracer;
+
+use std::cast;
+use extra::serialize::{Encodable, Encoder};
+
+// IMPORTANT: We rely on the fact that we never attempt to encode DOM objects using
+//            any encoder but JSTracer. Since we derive trace hooks automatically,
+//            we are unfortunately required to use generic types everywhere and
+//            unsafely cast to the concrete JSTracer we actually require.
+
+impl<T: Reflectable+Encodable<S>, S: Encoder> Encodable<S> for JS<T> {
+    fn encode(&self, s: &mut S) {
+        let s: &mut JSTracer = unsafe { cast::transmute(s) };
+        trace_reflector(s, "", self.reflector());
+    }
+}
+
+impl<S: Encoder> Encodable<S> for Reflector {
+    fn encode(&self, _s: &mut S) {
+    }
+}

src/components/script/dom/bindings/utils.rs

@@ -4,11 +4,13 @@
 
 use dom::bindings::codegen::PrototypeList;
 use dom::bindings::codegen::PrototypeList::MAX_PROTO_CHAIN_LENGTH;
+use dom::bindings::js::JS;
 use dom::window;
 use servo_util::str::DOMString;
 
 use std::libc::c_uint;
 use std::cast;
+use std::cmp::Eq;
 use std::hashmap::HashMap;
 use std::libc;
 use std::ptr;
@@ -32,7 +34,7 @@ use js::jsapi::{JSContext, JSObject, JSBool, jsid, JSClass, JSNative, JSTracer};
 use js::jsapi::{JSFunctionSpec, JSPropertySpec, JSVal, JSPropertyDescriptor};
 use js::jsapi::{JS_NewGlobalObject, JS_InitStandardClasses};
 use js::jsapi::{JSString, JS_CallTracer, JSTRACE_OBJECT};
-use js::jsapi::{JS_IsExceptionPending};
+use js::jsapi::{JS_IsExceptionPending, JS_AllowGC, JS_InhibitGC};
 use js::jsfriendapi::bindgen::JS_NewObjectWithUniqueType;
 use js::{JSPROP_ENUMERATE, JSVAL_NULL, JSCLASS_IS_GLOBAL, JSCLASS_IS_DOMJSCLASS};
 use js::{JSPROP_PERMANENT, JSID_VOID, JSPROP_NATIVE_ACCESSORS, JSPROP_GETTER};
@@ -174,6 +176,17 @@ pub fn unwrap_object<T>(obj: *JSObject, proto_id: PrototypeList::id::ID, proto_d
     }
 }
 
+pub fn unwrap_jsmanaged<T: Reflectable>(obj: *JSObject,
+                                        proto_id: PrototypeList::id::ID,
+                                        proto_depth: uint) -> Result<JS<T>, ()> {
+    let result: Result<*mut Box<T>, ()> = unwrap_object(obj, proto_id, proto_depth);
+    result.map(|unwrapped| {
+        unsafe {
+            JS::from_box(unwrapped)
+        }
+    })
+}
+
 pub fn unwrap_value<T>(val: *JSVal, proto_id: PrototypeList::id::ID, proto_depth: uint) -> Result<T, ()> {
     unsafe {
         let obj = RUST_JSVAL_TO_OBJECT(*val);
@@ -182,8 +195,11 @@ pub fn unwrap_value<T>(val: *JSVal, proto_id: PrototypeList::id::ID, proto_depth
 }
 
 pub unsafe fn squirrel_away<T>(x: @mut T) -> *Box<T> {
-    let y: *Box<T> = cast::transmute(x);
-    y
+    cast::transmute(x)
+}
+
+pub unsafe fn squirrel_away_unique<T>(x: ~T) -> *Box<T> {
+    cast::transmute(x)
 }
 
 pub fn jsstring_to_str(cx: *JSContext, s: *JSString) -> DOMString {
@@ -557,10 +573,6 @@ pub fn trace_reflector(tracer: *mut JSTracer, description: &str, reflector: &Ref
     }
 }
 
-pub fn trace_option<T: Reflectable>(tracer: *mut JSTracer, description: &str, option: Option<@mut T>) {
-    option.map(|some| trace_reflector(tracer, description, some.reflector()));
-}
-
 pub fn initialize_global(global: *JSObject) {
     let protoArray = @mut ([0 as *JSObject, ..PrototypeList::id::_ID_Count as uint]);
     unsafe {
@@ -579,21 +591,17 @@ pub trait Reflectable {
 }
 
 pub fn reflect_dom_object<T: Reflectable>
-        (obj:     @mut T,
+        (obj:     ~T,
          window:  &window::Window,
-         wrap_fn: extern "Rust" fn(*JSContext, *JSObject, @mut T) -> *JSObject)
-         ->       @mut T {
-    let cx = window.get_cx();
-    let scope = window.reflector().get_jsobject();
-    if wrap_fn(cx, scope, obj).is_null() {
-        fail!("Could not eagerly wrap object");
-    }
-    assert!(obj.reflector().get_jsobject().is_not_null());
-    obj
+         wrap_fn: extern "Rust" fn(*JSContext, *JSObject, ~T) -> *JSObject)
+         ->       JS<T> {
+    JS::new(obj, window, wrap_fn)
 }
 
+#[deriving(Eq)]
 pub struct Reflector {
-    object: *JSObject
+    object: *JSObject,
+    force_box_layout: @int,
 }
 
 impl Reflector {
@@ -610,7 +618,8 @@ impl Reflector {
 
     pub fn new() -> Reflector {
         Reflector {
-            object: ptr::null()
+            object: ptr::null(),
+            force_box_layout: @1,
         }
     }
 }
@@ -849,11 +858,11 @@ fn cx_for_dom_reflector(obj: *JSObject) -> *JSContext {
 }
 
 /// Returns the global object of the realm that the given DOM object was created in.
-pub fn global_object_for_dom_object<T: Reflectable>(obj: &mut T) -> *Box<window::Window> {
+pub fn global_object_for_dom_object<T: Reflectable>(obj: &T) -> *Box<window::Window> {
     global_object_for_js_object(obj.reflector().get_jsobject())
 }
 
-pub fn cx_for_dom_object<T: Reflectable>(obj: &mut T) -> *JSContext {
+pub fn cx_for_dom_object<T: Reflectable>(obj: &T) -> *JSContext {
     cx_for_dom_reflector(obj.reflector().get_jsobject())
 }
 
@@ -870,6 +879,26 @@ pub fn throw_method_failed_with_details<T>(cx: *JSContext,
     return 0;
 }
 
+/// Execute arbitrary code with the JS GC enabled, then disable it afterwards.
+pub fn with_gc_enabled<R>(cx: *JSContext, f: || -> R) -> R {
+    unsafe {
+        JS_AllowGC(cx);
+        let rv = f();
+        JS_InhibitGC(cx);
+        rv
+    }
+}
+
+/// Execute arbitrary code with the JS GC disabled, then enable it afterwards.
+pub fn with_gc_disabled<R>(cx: *JSContext, f: || -> R) -> R {
+    unsafe {
+        JS_InhibitGC(cx);
+        let rv = f();
+        JS_AllowGC(cx);
+        rv
+    }
+}
+
 /// Check if an element name is valid. See http://www.w3.org/TR/xml/#NT-Name
 /// for details.
 #[deriving(Eq)]

src/components/script/dom/blob.rs

@@ -2,32 +2,36 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::utils::Fallible;
 use dom::bindings::codegen::BlobBinding;
 use dom::window::Window;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct Blob {
     reflector_: Reflector,
-    window: @mut Window,
+    window: JS<Window>
 }
 
 impl Blob {
-    pub fn new_inherited(window: @mut Window) -> Blob {
+    pub fn new_inherited(window: JS<Window>) -> Blob {
         Blob {
             reflector_: Reflector::new(),
-            window: window,
+            window: window
         }
     }
 
-    pub fn new(window: @mut Window) -> @mut Blob {
-        reflect_dom_object(@mut Blob::new_inherited(window), window, BlobBinding::Wrap)
+    pub fn new(window: &JS<Window>) -> JS<Blob> {
+        reflect_dom_object(~Blob::new_inherited(window.clone()),
+                           window.get(),
+                           BlobBinding::Wrap)
     }
 }
 
 impl Blob {
-    pub fn Constructor(window: @mut Window) -> Fallible<@mut Blob> {
+    pub fn Constructor(window: &JS<Window>) -> Fallible<JS<Blob>> {
         Ok(Blob::new(window))
     }
 
@@ -39,8 +43,8 @@ impl Blob {
         ~""
     }
 
-    pub fn Slice(&self, _start: i64, _end: i64, _contentType: Option<DOMString>) -> @mut Blob {
-        Blob::new(self.window)
+    pub fn Slice(&self, _start: i64, _end: i64, _contentType: Option<DOMString>) -> JS<Blob> {
+        Blob::new(&self.window)
     }
 
     pub fn Close(&self) {}

src/components/script/dom/characterdata.rs

@@ -4,19 +4,34 @@
 
 //! DOM bindings for `CharacterData`.
 
+use dom::bindings::codegen::InheritTypes::CharacterDataDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Fallible, ErrorResult};
 use dom::bindings::utils::{Reflectable, Reflector};
-use dom::document::AbstractDocument;
-use dom::node::{Node, NodeTypeId};
+use dom::document::Document;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::node::{CommentNodeTypeId, Node, NodeTypeId, TextNodeTypeId, ProcessingInstructionNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct CharacterData {
     node: Node,
     data: DOMString,
 }
 
+impl CharacterDataDerived for EventTarget {
+    fn is_characterdata(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(TextNodeTypeId) |
+            NodeTargetTypeId(CommentNodeTypeId) |
+            NodeTargetTypeId(ProcessingInstructionNodeTypeId) => true,
+            _ => false
+        }
+    }
+}
+
 impl CharacterData {
-    pub fn new_inherited(id: NodeTypeId, data: DOMString, document: AbstractDocument) -> CharacterData {
+    pub fn new_inherited(id: NodeTypeId, data: DOMString, document: JS<Document>) -> CharacterData {
         CharacterData {
             node: Node::new_inherited(id, document),
             data: data

src/components/script/dom/clientrect.rs

@@ -3,21 +3,23 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::ClientRectBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::window::Window;
 use servo_util::geometry::Au;
 
+#[deriving(Encodable)]
 pub struct ClientRect {
     reflector_: Reflector,
     top: f32,
     bottom: f32,
     left: f32,
     right: f32,
-    window: @mut Window,
+    window: JS<Window>,
 }
 
 impl ClientRect {
-    pub fn new_inherited(window: @mut Window,
+    pub fn new_inherited(window: JS<Window>,
                          top: Au, bottom: Au,
                          left: Au, right: Au) -> ClientRect {
         ClientRect {
@@ -30,11 +32,11 @@ impl ClientRect {
         }
     }
 
-    pub fn new(window: @mut Window,
+    pub fn new(window: &JS<Window>,
                top: Au, bottom: Au,
-               left: Au, right: Au) -> @mut ClientRect {
-        let rect = ClientRect::new_inherited(window, top, bottom, left, right);
-        reflect_dom_object(@mut rect, window, ClientRectBinding::Wrap)
+               left: Au, right: Au) -> JS<ClientRect> {
+        let rect = ClientRect::new_inherited(window.clone(), top, bottom, left, right);
+        reflect_dom_object(~rect, window.get(), ClientRectBinding::Wrap)
     }
 
 

src/components/script/dom/clientrectlist.rs

@@ -3,19 +3,21 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::ClientRectListBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::clientrect::ClientRect;
 use dom::window::Window;
 
+#[deriving(Encodable)]
 pub struct ClientRectList {
     reflector_: Reflector,
-    rects: ~[@mut ClientRect],
-    window: @mut Window,
+    rects: ~[JS<ClientRect>],
+    window: JS<Window>,
 }
 
 impl ClientRectList {
-    pub fn new_inherited(window: @mut Window,
-                         rects: ~[@mut ClientRect]) -> ClientRectList {
+    pub fn new_inherited(window: JS<Window>,
+                         rects: ~[JS<ClientRect>]) -> ClientRectList {
         ClientRectList {
             reflector_: Reflector::new(),
             rects: rects,
@@ -23,25 +25,25 @@ impl ClientRectList {
         }
     }
 
-    pub fn new(window: @mut Window,
-               rects: ~[@mut ClientRect]) -> @mut ClientRectList {
-        reflect_dom_object(@mut ClientRectList::new_inherited(window, rects),
-                           window, ClientRectListBinding::Wrap)
+    pub fn new(window: &JS<Window>,
+               rects: ~[JS<ClientRect>]) -> JS<ClientRectList> {
+        reflect_dom_object(~ClientRectList::new_inherited(window.clone(), rects),
+                           window.get(), ClientRectListBinding::Wrap)
     }
 
     pub fn Length(&self) -> u32 {
         self.rects.len() as u32
     }
 
-    pub fn Item(&self, index: u32) -> Option<@mut ClientRect> {
+    pub fn Item(&self, index: u32) -> Option<JS<ClientRect>> {
         if index < self.rects.len() as u32 {
-            Some(self.rects[index])
+            Some(self.rects[index].clone())
         } else {
             None
         }
     }
 
-    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<@mut ClientRect> {
+    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<JS<ClientRect>> {
         *found = index < self.rects.len() as u32;
         self.Item(index)
     }

src/components/script/dom/comment.rs

@@ -2,32 +2,45 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::codegen::InheritTypes::CommentDerived;
 use dom::bindings::codegen::CommentBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::Fallible;
 use dom::characterdata::CharacterData;
-use dom::document::AbstractDocument;
-use dom::node::{AbstractNode, CommentNodeTypeId, Node};
+use dom::document::Document;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::node::{CommentNodeTypeId, Node};
 use dom::window::Window;
 use servo_util::str::DOMString;
 
 /// An HTML comment.
+#[deriving(Encodable)]
 pub struct Comment {
     characterdata: CharacterData,
 }
 
+impl CommentDerived for EventTarget {
+    fn is_comment(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(CommentNodeTypeId) => true,
+            _ => false
+        }
+    }
+}
+
 impl Comment {
-    pub fn new_inherited(text: DOMString, document: AbstractDocument) -> Comment {
+    pub fn new_inherited(text: DOMString, document: JS<Document>) -> Comment {
         Comment {
             characterdata: CharacterData::new_inherited(CommentNodeTypeId, text, document)
         }
     }
 
-    pub fn new(text: DOMString, document: AbstractDocument) -> AbstractNode {
-        let node = Comment::new_inherited(text, document);
-        Node::reflect_node(@mut node, document, CommentBinding::Wrap)
+    pub fn new(text: DOMString, document: &JS<Document>) -> JS<Comment> {
+        let node = Comment::new_inherited(text, document.clone());
+        Node::reflect_node(~node, document, CommentBinding::Wrap)
     }
 
-    pub fn Constructor(owner: @mut Window, data: DOMString) -> Fallible<AbstractNode> {
-        Ok(Comment::new(data, owner.Document()))
+    pub fn Constructor(owner: &JS<Window>, data: DOMString) -> Fallible<JS<Comment>> {
+        Ok(Comment::new(data, &owner.get().Document()))
     }
 }

src/components/script/dom/console.rs

@@ -2,11 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::codegen::ConsoleBinding;
+use dom::bindings::js::JS;
+use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::window::Window;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct Console {
     reflector_: Reflector
 }
@@ -18,8 +20,8 @@ impl Console {
         }
     }
 
-    pub fn new(window: &Window) -> @mut Console {
-        reflect_dom_object(@mut Console::new_inherited(), window, ConsoleBinding::Wrap)
+    pub fn new(window: &Window) -> JS<Console> {
+        reflect_dom_object(~Console::new_inherited(), window, ConsoleBinding::Wrap)
     }
 
     pub fn Log(&self, message: DOMString) {

src/components/script/dom/document.rs

@@ -2,25 +2,35 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use dom::comment::Comment;
+use dom::bindings::codegen::InheritTypes::{DocumentDerived, EventCast, HTMLElementCast};
+use dom::bindings::codegen::InheritTypes::{DocumentBase, NodeCast, DocumentCast};
+use dom::bindings::codegen::InheritTypes::{HTMLHeadElementCast, TextCast, ElementCast};
+use dom::bindings::codegen::InheritTypes::{DocumentTypeCast, HTMLHtmlElementCast};
 use dom::bindings::codegen::DocumentBinding;
-use dom::bindings::utils::{Reflectable, Reflector, Traceable, reflect_dom_object};
+use dom::bindings::js::JS;
+use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::utils::{ErrorResult, Fallible, NotSupported, InvalidCharacter, HierarchyRequest};
 use dom::bindings::utils::{xml_name_type, InvalidXMLName};
+use dom::comment::Comment;
 use dom::documentfragment::DocumentFragment;
+use dom::documenttype;
 use dom::domimplementation::DOMImplementation;
 use dom::element::{Element};
-use dom::element::{HTMLHtmlElementTypeId, HTMLHeadElementTypeId, HTMLTitleElementTypeId, HTMLBodyElementTypeId, HTMLFrameSetElementTypeId};
-use dom::event::{AbstractEvent, Event};
+use dom::element::{HTMLHtmlElementTypeId, HTMLHeadElementTypeId, HTMLTitleElementTypeId};
+use dom::element::{HTMLBodyElementTypeId, HTMLFrameSetElementTypeId};
+use dom::event::Event;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlcollection::HTMLCollection;
-use dom::htmldocument::HTMLDocument;
+use dom::htmlelement::HTMLElement;
+use dom::htmlheadelement::HTMLHeadElement;
+use dom::htmlhtmlelement::HTMLHtmlElement;
+use dom::htmltitleelement::HTMLTitleElement;
 use dom::mouseevent::MouseEvent;
-use dom::node::{AbstractNode, Node, ElementNodeTypeId, DocumentNodeTypeId};
+use dom::node::{Node, ElementNodeTypeId, DocumentNodeTypeId, NodeHelpers, INode};
 use dom::text::Text;
 use dom::processinginstruction::ProcessingInstruction;
 use dom::uievent::UIEvent;
 use dom::window::Window;
-use dom::htmltitleelement::HTMLTitleElement;
 use html::hubbub_html_parser::build_element_from_tag;
 use hubbub::hubbub::{QuirksMode, NoQuirks, LimitedQuirks, FullQuirks};
 use layout_interface::{DocumentDamageLevel, ContentChangedDocumentDamage};
@@ -28,103 +38,74 @@ use servo_util::namespace::Null;
 use servo_util::str::DOMString;
 
 use extra::url::{Url, from_str};
-use js::jsapi::{JSObject, JSContext, JSTracer};
+use js::jsapi::{JSObject, JSContext};
 use std::ascii::StrAsciiExt;
-use std::cast;
 use std::hashmap::HashMap;
-use std::unstable::raw::Box;
 
-#[deriving(Eq)]
+use extra::serialize::{Encoder, Encodable};
+
+#[deriving(Eq,Encodable)]
 pub enum DocumentTypeId {
     PlainDocumentTypeId,
     HTMLDocumentTypeId
 }
 
-#[deriving(Eq)]
-pub struct AbstractDocument {
-    document: *mut Box<Document>
-}
-
-impl AbstractDocument {
-    pub fn document<'a>(&'a self) -> &'a Document {
-        unsafe {
-            &(*self.document).data
-        }
-    }
-
-    pub fn mut_document<'a>(&'a self) -> &'a mut Document {
-        unsafe {
-            &mut (*self.document).data
-        }
-    }
-
-    unsafe fn transmute<T, R>(&self, f: |&T| -> R) -> R {
-        let box_: *Box<T> = cast::transmute(self.document);
-        f(&(*box_).data)
-    }
-
-    pub fn with_html<R>(&self, callback: |&HTMLDocument| -> R) -> R {
-        match self.document().doctype {
-            HTML => unsafe { self.transmute(callback) },
-            _ => fail!("attempt to downcast a non-HTMLDocument to HTMLDocument")
-        }
-    }
-
-    pub fn from_box<T>(ptr: *mut Box<T>) -> AbstractDocument {
-        AbstractDocument {
-            document: ptr as *mut Box<Document>
-        }
-    }
-
-    pub fn from_node(node: AbstractNode) -> AbstractDocument {
-        if !node.is_document() {
-            fail!("node is not a document");
-        }
-        unsafe {
-            cast::transmute(node)
-        }
-    }
-}
-
-#[deriving(Eq)]
+#[deriving(Eq,Encodable)]
 pub enum DocumentType {
     HTML,
     SVG,
     XML
 }
 
+#[deriving(Encodable)]
 pub struct Document {
     node: Node,
     reflector_: Reflector,
-    window: @mut Window,
+    window: JS<Window>,
     doctype: DocumentType,
-    idmap: HashMap<DOMString, AbstractNode>,
-    implementation: Option<@mut DOMImplementation>,
+    idmap: HashMap<DOMString, JS<Element>>,
+    implementation: Option<JS<DOMImplementation>>,
     content_type: DOMString,
+    encoding_name: DOMString,
+    extra: Untraceable,
+}
+
+struct Untraceable {
     url: Url,
     quirks_mode: QuirksMode,
-    encoding_name: DOMString,
+}
+
+impl<S: Encoder> Encodable<S> for Untraceable {
+    fn encode(&self, _: &mut S) {
+    }
+}
+
+impl DocumentDerived for EventTarget {
+    fn is_document(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(DocumentNodeTypeId(_)) => true,
+            _ => false
+        }
+    }
 }
 
 impl Document {
-    pub fn reflect_document<D: Reflectable>
-            (document:  @mut D,
-             window:    @mut Window,
-             wrap_fn:   extern "Rust" fn(*JSContext, *JSObject, @mut D) -> *JSObject)
-             -> AbstractDocument {
+    pub fn reflect_document<D: Reflectable+DocumentBase>
+            (document:  ~D,
+             window:    &JS<Window>,
+             wrap_fn:   extern "Rust" fn(*JSContext, *JSObject, ~D) -> *JSObject)
+             -> JS<D> {
         assert!(document.reflector().get_jsobject().is_null());
-        let document = reflect_dom_object(document, window, wrap_fn);
-        assert!(document.reflector().get_jsobject().is_not_null());
+        let raw_doc = reflect_dom_object(document, window.get(), wrap_fn);
+        assert!(raw_doc.reflector().get_jsobject().is_not_null());
 
-        // JS object now owns the Document, so transmute_copy is needed
-        let abstract = AbstractDocument {
-            document: unsafe { cast::transmute_copy(&document) }
-        };
-        abstract.mut_document().node.set_owner_doc(abstract);
-        abstract
+        let document = DocumentCast::from(&raw_doc);
+        let mut node: JS<Node> = NodeCast::from(&document);
+        node.get_mut().set_owner_doc(&document);
+        raw_doc
     }
 
-    pub fn new_inherited(window: @mut Window, url: Option<Url>, doctype: DocumentType, content_type: Option<DOMString>) -> Document {
+    pub fn new_inherited(window: JS<Window>, url: Option<Url>, doctype: DocumentType, content_type: Option<DOMString>) -> Document {
         let node_type = match doctype {
             HTML => HTMLDocumentTypeId,
             SVG | XML => PlainDocumentTypeId
@@ -145,40 +126,32 @@ impl Document {
                     SVG | XML => ~"application/xml"
                 }
             },
+            extra: Untraceable {
                 url: match url {
                     None => from_str("about:blank").unwrap(),
                     Some(_url) => _url
                 },
                 // http://dom.spec.whatwg.org/#concept-document-quirks
                 quirks_mode: NoQuirks,
+            },
             // http://dom.spec.whatwg.org/#concept-document-encoding
             encoding_name: ~"utf-8",
         }
     }
 
-    pub fn new(window: @mut Window, url: Option<Url>, doctype: DocumentType, content_type: Option<DOMString>) -> AbstractDocument {
-        let document = Document::new_inherited(window, url, doctype, content_type);
-        Document::reflect_document(@mut document, window, DocumentBinding::Wrap)
+    pub fn new(window: &JS<Window>, url: Option<Url>, doctype: DocumentType, content_type: Option<DOMString>) -> JS<Document> {
+        let document = Document::new_inherited(window.clone(), url, doctype, content_type);
+        Document::reflect_document(~document, window, DocumentBinding::Wrap)
     }
 }
 
 impl Document {
     // http://dom.spec.whatwg.org/#dom-document
-    pub fn Constructor(owner: @mut Window) -> Fallible<AbstractDocument> {
+    pub fn Constructor(owner: &JS<Window>) -> Fallible<JS<Document>> {
         Ok(Document::new(owner, None, XML, None))
     }
 }
 
-impl Reflectable for AbstractDocument {
-    fn reflector<'a>(&'a self) -> &'a Reflector {
-        self.document().reflector()
-    }
-
-    fn mut_reflector<'a>(&'a mut self) -> &'a mut Reflector {
-        self.mut_document().mut_reflector()
-    }
-}
-
 impl Reflectable for Document {
     fn reflector<'a>(&'a self) -> &'a Reflector {
         self.node.reflector()
@@ -191,16 +164,16 @@ impl Reflectable for Document {
 
 impl Document {
     // http://dom.spec.whatwg.org/#dom-document-implementation
-    pub fn Implementation(&mut self) -> @mut DOMImplementation {
+    pub fn Implementation(&mut self) -> JS<DOMImplementation> {
         if self.implementation.is_none() {
-            self.implementation = Some(DOMImplementation::new(self.window));
+            self.implementation = Some(DOMImplementation::new(&self.window));
         }
-        self.implementation.unwrap()
+        self.implementation.get_ref().clone()
     }
 
     // http://dom.spec.whatwg.org/#dom-document-url
     pub fn URL(&self) -> DOMString {
-        self.url.to_str()
+        self.extra.url.to_str()
     }
 
     // http://dom.spec.whatwg.org/#dom-document-documenturi
@@ -210,14 +183,14 @@ impl Document {
 
     // http://dom.spec.whatwg.org/#dom-document-compatmode
     pub fn CompatMode(&self) -> DOMString {
-        match self.quirks_mode {
+        match self.extra.quirks_mode {
             NoQuirks => ~"CSS1Compat",
             LimitedQuirks | FullQuirks => ~"BackCompat"
         }
     }
 
     pub fn set_quirks_mode(&mut self, mode: QuirksMode) {
-        self.quirks_mode = mode;
+        self.extra.quirks_mode = mode;
     }
 
     // http://dom.spec.whatwg.org/#dom-document-characterset
@@ -235,43 +208,44 @@ impl Document {
     }
 
     // http://dom.spec.whatwg.org/#dom-document-doctype
-    pub fn GetDoctype(&self) -> Option<AbstractNode> {
+    pub fn GetDoctype(&self) -> Option<JS<documenttype::DocumentType>> {
         self.node.children().find(|child| child.is_doctype())
+                            .map(|node| DocumentTypeCast::to(&node))
     }
 
     // http://dom.spec.whatwg.org/#dom-document-documentelement
-    pub fn GetDocumentElement(&self) -> Option<AbstractNode> {
+    pub fn GetDocumentElement(&self) -> Option<JS<Element>> {
         self.node.child_elements().next()
     }
 
     // http://dom.spec.whatwg.org/#dom-document-getelementsbytagname
-    pub fn GetElementsByTagName(&self, tag: DOMString) -> @mut HTMLCollection {
+    pub fn GetElementsByTagName(&self, tag: DOMString) -> JS<HTMLCollection> {
         self.createHTMLCollection(|elem| elem.tag_name == tag)
     }
 
     // http://dom.spec.whatwg.org/#dom-document-getelementsbytagnamens
-    pub fn GetElementsByTagNameNS(&self, _ns: Option<DOMString>, _tag: DOMString) -> @mut HTMLCollection {
-        HTMLCollection::new(self.window, ~[])
+    pub fn GetElementsByTagNameNS(&self, _ns: Option<DOMString>, _tag: DOMString) -> JS<HTMLCollection> {
+        HTMLCollection::new(&self.window, ~[])
     }
 
     // http://dom.spec.whatwg.org/#dom-document-getelementsbyclassname
-    pub fn GetElementsByClassName(&self, _class: DOMString) -> @mut HTMLCollection {
-        HTMLCollection::new(self.window, ~[])
+    pub fn GetElementsByClassName(&self, _class: DOMString) -> JS<HTMLCollection> {
+        HTMLCollection::new(&self.window, ~[])
     }
 
     // http://dom.spec.whatwg.org/#dom-nonelementparentnode-getelementbyid
-    pub fn GetElementById(&self, id: DOMString) -> Option<AbstractNode> {
+    pub fn GetElementById(&self, id: DOMString) -> Option<JS<Element>> {
         // TODO: "in tree order, within the context object's tree"
         // http://dom.spec.whatwg.org/#dom-document-getelementbyid.
         match self.idmap.find_equiv(&id) {
             None => None,
-            Some(node) => Some(*node),
+            Some(node) => Some(node.clone()),
         }
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createelement
-    pub fn CreateElement(&self, abstract_self: AbstractDocument, local_name: DOMString)
-                         -> Fallible<AbstractNode> {
+    pub fn CreateElement(&self, abstract_self: &JS<Document>, local_name: DOMString)
+                         -> Fallible<JS<Element>> {
         if xml_name_type(local_name) == InvalidXMLName {
             debug!("Not a valid element name");
             return Err(InvalidCharacter);
@@ -281,24 +255,24 @@ impl Document {
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createdocumentfragment
-    pub fn CreateDocumentFragment(&self, abstract_self: AbstractDocument) -> AbstractNode {
+    pub fn CreateDocumentFragment(&self, abstract_self: &JS<Document>) -> JS<DocumentFragment> {
         DocumentFragment::new(abstract_self)
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createtextnode
-    pub fn CreateTextNode(&self, abstract_self: AbstractDocument, data: DOMString)
-                          -> AbstractNode {
+    pub fn CreateTextNode(&self, abstract_self: &JS<Document>, data: DOMString)
+                          -> JS<Text> {
         Text::new(data, abstract_self)
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createcomment
-    pub fn CreateComment(&self, abstract_self: AbstractDocument, data: DOMString) -> AbstractNode {
+    pub fn CreateComment(&self, abstract_self: &JS<Document>, data: DOMString) -> JS<Comment> {
         Comment::new(data, abstract_self)
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createprocessinginstruction
-    pub fn CreateProcessingInstruction(&self, abstract_self: AbstractDocument, target: DOMString,
-                                       data: DOMString) -> Fallible<AbstractNode> {
+    pub fn CreateProcessingInstruction(&self, abstract_self: &JS<Document>, target: DOMString,
+                                       data: DOMString) -> Fallible<JS<ProcessingInstruction>> {
         // Step 1.
         if xml_name_type(target) == InvalidXMLName {
             return Err(InvalidCharacter);
@@ -314,41 +288,34 @@ impl Document {
     }
 
     // http://dom.spec.whatwg.org/#dom-document-createevent
-    pub fn CreateEvent(&self, interface: DOMString) -> Fallible<AbstractEvent> {
+    pub fn CreateEvent(&self, interface: DOMString) -> Fallible<JS<Event>> {
         match interface.as_slice() {
-            "UIEvents" => Ok(UIEvent::new(self.window)),
-            "MouseEvents" => Ok(MouseEvent::new(self.window)),
-            "HTMLEvents" => Ok(Event::new(self.window)),
+            "UIEvents" => Ok(EventCast::from(&UIEvent::new(&self.window))),
+            "MouseEvents" => Ok(EventCast::from(&MouseEvent::new(&self.window))),
+            "HTMLEvents" => Ok(Event::new(&self.window)),
             _ => Err(NotSupported)
         }
     }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#document.title
-    pub fn Title(&self, _: AbstractDocument) -> DOMString {
+    pub fn Title(&self, _: &JS<Document>) -> DOMString {
         let mut title = ~"";
         match self.doctype {
             SVG => {
                 fail!("no SVG document yet")
             },
             _ => {
-                match self.GetDocumentElement() {
-                    None => {},
-                    Some(root) => {
-                        for node in root.traverse_preorder() {
-                            if node.type_id() != ElementNodeTypeId(HTMLTitleElementTypeId) {
-                                continue;
+                self.GetDocumentElement().map(|root| {
+                    let root: JS<Node> = NodeCast::from(&root);
+                    root.traverse_preorder()
+                        .find(|node| node.type_id() == ElementNodeTypeId(HTMLTitleElementTypeId))
+                        .map(|title_elem| {
+                            for child in title_elem.children() {
+                                let text: JS<Text> = TextCast::to(&child);
+                                title.push_str(text.get().characterdata.data.as_slice());
                             }
-                            for child in node.children() {
-                                if child.is_text() {
-                                    child.with_imm_text(|text| {
-                                        title.push_str(text.characterdata.data.as_slice());
                         });
-                                }
-                            }
-                            break;
-                        }
-                    }
-                }
+                });
             }
         }
         let v: ~[&str] = title.words().collect();
@@ -358,85 +325,81 @@ impl Document {
     }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#document.title
-    pub fn SetTitle(&self, abstract_self: AbstractDocument, title: DOMString) -> ErrorResult {
+    pub fn SetTitle(&self, abstract_self: &JS<Document>, title: DOMString) -> ErrorResult {
         match self.doctype {
             SVG => {
                 fail!("no SVG document yet")
             },
             _ => {
-                match self.GetDocumentElement() {
-                    None => {},
-                    Some(root) => {
-                        for node in root.traverse_preorder() {
-                            if node.type_id() != ElementNodeTypeId(HTMLHeadElementTypeId) {
-                                continue;
-                            }
-                            let mut has_title = false;
-                            for child in node.children() {
-                                if child.type_id() != ElementNodeTypeId(HTMLTitleElementTypeId) {
-                                    continue;
-                                }
-                                has_title = true;
-                                for title_child in child.children() {
-                                    child.RemoveChild(title_child);
-                                }
-                                child.AppendChild(self.CreateTextNode(abstract_self, title.clone()));
-                                break;
-                            }
-                            if !has_title {
-                                let new_title = HTMLTitleElement::new(~"title", abstract_self);
-                                new_title.AppendChild(self.CreateTextNode(abstract_self, title.clone()));
-                                node.AppendChild(new_title);
-                            }
-                            break;
-                        }
+                self.GetDocumentElement().map(|root| {
+                    let root: JS<Node> = NodeCast::from(&root);
+                    let mut head_node = root.traverse_preorder().find(|child| {
+                        child.get().type_id == ElementNodeTypeId(HTMLHeadElementTypeId)
+                    });
+                    head_node.as_mut().map(|head| {
+
+                        let mut title_node = head.children().find(|child| {
+                            child.get().type_id == ElementNodeTypeId(HTMLTitleElementTypeId)
+                        });
+
+                        title_node.as_mut().map(|title_node| {
+                            for mut title_child in title_node.children() {
+                                title_node.RemoveChild(&mut title_child);
                             }
+                            let new_text = self.CreateTextNode(abstract_self, title.clone());
+                            title_node.AppendChild(&mut NodeCast::from(&new_text));
+                        });
+
+                        if title_node.is_none() {
+                            let mut new_title: JS<Node> =
+                                NodeCast::from(&HTMLTitleElement::new(~"title", abstract_self));
+                            let new_text = self.CreateTextNode(abstract_self, title.clone());
+                            new_title.AppendChild(&mut NodeCast::from(&new_text));
+                            head.AppendChild(&mut new_title);
                         }
+                    });
+                });
             }
         }
         Ok(())
     }
 
-    fn get_html_element(&self) -> Option<AbstractNode> {
+    fn get_html_element(&self) -> Option<JS<HTMLHtmlElement>> {
         self.GetDocumentElement().filtered(|root| {
-            match root.type_id() {
-                ElementNodeTypeId(HTMLHtmlElementTypeId) => true,
-                _ => false
-            }
-        })
+            root.get().node.type_id == ElementNodeTypeId(HTMLHtmlElementTypeId)
+        }).map(|elem| HTMLHtmlElementCast::to(&elem))
     }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-head
-    pub fn GetHead(&self) -> Option<AbstractNode> {
+    pub fn GetHead(&self) -> Option<JS<HTMLHeadElement>> {
         self.get_html_element().and_then(|root| {
-            root.children().find(|child| {
+            let node: JS<Node> = NodeCast::from(&root);
+            node.children().find(|child| {
                 child.type_id() == ElementNodeTypeId(HTMLHeadElementTypeId)
-            })
+            }).map(|node| HTMLHeadElementCast::to(&node))
         })
     }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-body
-    pub fn GetBody(&self, _: AbstractDocument) -> Option<AbstractNode> {
-        match self.get_html_element() {
-            None => None,
-            Some(root) => {
-                root.children().find(|child| {
+    pub fn GetBody(&self, _: &JS<Document>) -> Option<JS<HTMLElement>> {
+        self.get_html_element().and_then(|root| {
+            let node: JS<Node> = NodeCast::from(&root);
+            node.children().find(|child| {
                 match child.type_id() {
                     ElementNodeTypeId(HTMLBodyElementTypeId) |
                     ElementNodeTypeId(HTMLFrameSetElementTypeId) => true,
                     _ => false
                 }
+            }).map(|node| HTMLElementCast::to(&node))
         })
     }
-        }
-    }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-body
-    pub fn SetBody(&self, abstract_self: AbstractDocument, new_body: Option<AbstractNode>) -> ErrorResult {
+    pub fn SetBody(&self, abstract_self: &JS<Document>, new_body: Option<JS<HTMLElement>>) -> ErrorResult {
         // Step 1.
         match new_body {
-            Some(node) => {
-                match node.type_id() {
+            Some(ref node) => {
+                match node.get().element.node.type_id {
                     ElementNodeTypeId(HTMLBodyElementTypeId) | ElementNodeTypeId(HTMLFrameSetElementTypeId) => {}
                     _ => return Err(HierarchyRequest)
                 }
@@ -445,7 +408,7 @@ impl Document {
         }
 
         // Step 2.
-        let old_body: Option<AbstractNode> = self.GetBody(abstract_self);
+        let old_body: Option<JS<HTMLElement>> = self.GetBody(abstract_self);
         if old_body == new_body {
             return Ok(());
         }
@@ -455,41 +418,46 @@ impl Document {
             // Step 4.
             None => return Err(HierarchyRequest),
             Some(root) => {
+                let mut new_body: JS<Node> = NodeCast::from(&new_body.unwrap());
+                let mut root: JS<Node> = NodeCast::from(&root);
                 match old_body {
-                    Some(child) => { root.ReplaceChild(new_body.unwrap(), child); }
-                    None => { root.AppendChild(new_body.unwrap()); }
+                    Some(child) => {
+                        let mut child: JS<Node> = NodeCast::from(&child);
+                        root.ReplaceChild(&mut new_body, &mut child)
                     }
+                    None => root.AppendChild(&mut new_body)
+                };
             }
         }
         Ok(())
     }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-document-getelementsbyname
-    pub fn GetElementsByName(&self, name: DOMString) -> @mut HTMLCollection {
+    pub fn GetElementsByName(&self, name: DOMString) -> JS<HTMLCollection> {
         self.createHTMLCollection(|elem| {
             elem.get_attribute(Null, "name").map_default(false, |attr| {
-                attr.value_ref() == name
+                attr.get().value_ref() == name
             })
         })
     }
 
-    pub fn createHTMLCollection(&self, callback: |elem: &Element| -> bool) -> @mut HTMLCollection {
+    pub fn createHTMLCollection(&self, callback: |elem: &Element| -> bool) -> JS<HTMLCollection> {
         let mut elements = ~[];
         match self.GetDocumentElement() {
             None => {},
             Some(root) => {
+                let root: JS<Node> = NodeCast::from(&root);
                 for child in root.traverse_preorder() {
                     if child.is_element() {
-                        child.with_imm_element(|elem| {
-                            if callback(elem) {
-                                elements.push(child);
-                            }
-                        });
+                        let elem: JS<Element> = ElementCast::to(&child);
+                        if callback(elem.get()) {
+                            elements.push(elem);
                         }
                     }
                 }
             }
-        HTMLCollection::new(self.window, elements)
+        }
+        HTMLCollection::new(&self.window, elements)
     }
 
     pub fn content_changed(&self) {
@@ -497,22 +465,22 @@ impl Document {
     }
 
     pub fn damage_and_reflow(&self, damage: DocumentDamageLevel) {
-        self.window.damage_and_reflow(damage);
+        self.window.get().damage_and_reflow(damage);
     }
 
     pub fn wait_until_safe_to_modify_dom(&self) {
-        self.window.wait_until_safe_to_modify_dom();
+        self.window.get().wait_until_safe_to_modify_dom();
     }
 
-    pub fn register_nodes_with_id(&mut self, root: &AbstractNode) {
-        foreach_ided_elements(root, |id: &DOMString, abstract_node: &AbstractNode| {
+    pub fn register_nodes_with_id(&mut self, root: &JS<Element>) {
+        foreach_ided_elements(root, |id: &DOMString, abstract_node: &JS<Element>| {
             // TODO: "in tree order, within the context object's tree"
             // http://dom.spec.whatwg.org/#dom-document-getelementbyid.
-            self.idmap.find_or_insert(id.clone(), *abstract_node);
+            self.idmap.find_or_insert(id.clone(), abstract_node.clone());
         });
     }
 
-    pub fn unregister_nodes_with_id(&mut self, root: &AbstractNode) {
+    pub fn unregister_nodes_with_id(&mut self, root: &JS<Element>) {
         foreach_ided_elements(root, |id: &DOMString, _| {
             // TODO: "in tree order, within the context object's tree"
             // http://dom.spec.whatwg.org/#dom-document-getelementbyid.
@@ -521,7 +489,7 @@ impl Document {
     }
 
     pub fn update_idmap(&mut self,
-                        abstract_self: AbstractNode,
+                        abstract_self: &JS<Element>,
                         new_id: Option<DOMString>,
                         old_id: Option<DOMString>) {
         // remove old ids:
@@ -539,11 +507,11 @@ impl Document {
             Some(new_id) => {
                 // TODO: support the case if multiple elements
                 // which haves same id are in the same document.
-                self.idmap.mangle(new_id, abstract_self,
-                                  |_, new_node: AbstractNode| -> AbstractNode {
+                self.idmap.mangle(new_id, abstract_self.clone(),
+                                  |_, new_node: JS<Element>| -> JS<Element> {
                                       new_node
                                   },
-                                  |_, old_node: &mut AbstractNode, new_node: AbstractNode| {
+                                  |_, old_node: &mut JS<Element>, new_node: JS<Element>| {
                                       *old_node = new_node;
                                   });
             }
@@ -553,25 +521,19 @@ impl Document {
 }
 
 #[inline(always)]
-fn foreach_ided_elements(root: &AbstractNode, callback: |&DOMString, &AbstractNode|) {
+fn foreach_ided_elements(root: &JS<Element>, callback: |&DOMString, &JS<Element>|) {
+    let root: JS<Node> = NodeCast::from(root);
     for node in root.traverse_preorder() {
         if !node.is_element() {
             continue;
         }
 
-        node.with_imm_element(|element| {
-            match element.get_attribute(Null, "id") {
+        let element: JS<Element> = ElementCast::to(&node);
+        match element.get().get_attribute(Null, "id") {
             Some(id) => {
-                    callback(&id.Value(), &node);
+                callback(&id.get().Value(), &element);
             }
             None => ()
         }
-        });
-    }
-}
-
-impl Traceable for Document {
-    fn trace(&self, tracer: *mut JSTracer) {
-        self.node.trace(tracer);
     }
 }

src/components/script/dom/documentfragment.rs

@@ -2,32 +2,45 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::codegen::InheritTypes::DocumentFragmentDerived;
 use dom::bindings::codegen::DocumentFragmentBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::Fallible;
-use dom::document::AbstractDocument;
-use dom::node::{AbstractNode, DocumentFragmentNodeTypeId, Node};
+use dom::document::Document;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::node::{DocumentFragmentNodeTypeId, Node};
 use dom::window::Window;
 
+#[deriving(Encodable)]
 pub struct DocumentFragment {
     node: Node,
 }
 
+impl DocumentFragmentDerived for EventTarget {
+    fn is_documentfragment(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(DocumentFragmentNodeTypeId) => true,
+            _ => false
+        }
+    }
+}
+
 impl DocumentFragment {
     /// Creates a new DocumentFragment.
-    pub fn new_inherited(document: AbstractDocument) -> DocumentFragment {
+    pub fn new_inherited(document: JS<Document>) -> DocumentFragment {
         DocumentFragment {
             node: Node::new_inherited(DocumentFragmentNodeTypeId, document),
         }
     }
 
-    pub fn new(document: AbstractDocument) -> AbstractNode {
-        let node = DocumentFragment::new_inherited(document);
-        Node::reflect_node(@mut node, document, DocumentFragmentBinding::Wrap)
+    pub fn new(document: &JS<Document>) -> JS<DocumentFragment> {
+        let node = DocumentFragment::new_inherited(document.clone());
+        Node::reflect_node(~node, document, DocumentFragmentBinding::Wrap)
     }
 }
 
 impl DocumentFragment {
-    pub fn Constructor(owner: @mut Window) -> Fallible<AbstractNode> {
-        Ok(DocumentFragment::new(owner.Document()))
+    pub fn Constructor(owner: &JS<Window>) -> Fallible<JS<DocumentFragment>> {
+        Ok(DocumentFragment::new(&owner.get().Document()))
     }
 }

src/components/script/dom/documenttype.rs

@@ -2,12 +2,16 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::codegen::InheritTypes::DocumentTypeDerived;
 use dom::bindings::codegen::DocumentTypeBinding;
-use dom::document::AbstractDocument;
-use dom::node::{AbstractNode, Node, DoctypeNodeTypeId};
+use dom::bindings::js::JS;
+use dom::document::Document;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::node::{Node, DoctypeNodeTypeId};
 use servo_util::str::DOMString;
 
 /// The `DOCTYPE` tag.
+#[deriving(Encodable)]
 pub struct DocumentType {
     node: Node,
     name: DOMString,
@@ -15,11 +19,20 @@ pub struct DocumentType {
     system_id: DOMString,
 }
 
+impl DocumentTypeDerived for EventTarget {
+    fn is_documenttype(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(DoctypeNodeTypeId) => true,
+            _ => false
+        }
+    }
+}
+
 impl DocumentType {
     pub fn new_inherited(name: DOMString,
                          public_id: Option<DOMString>,
                          system_id: Option<DOMString>,
-                         document: AbstractDocument)
+                         document: JS<Document>)
             -> DocumentType {
         DocumentType {
             node: Node::new_inherited(DoctypeNodeTypeId, document),
@@ -32,13 +45,13 @@ impl DocumentType {
     pub fn new(name: DOMString,
                public_id: Option<DOMString>,
                system_id: Option<DOMString>,
-               document: AbstractDocument)
-               -> AbstractNode {
+               document: &JS<Document>)
+               -> JS<DocumentType> {
         let documenttype = DocumentType::new_inherited(name,
                                                        public_id,
                                                        system_id,
-                                                       document);
-        Node::reflect_node(@mut documenttype, document, DocumentTypeBinding::Wrap)
+                                                       document.clone());
+        Node::reflect_node(~documenttype, document, DocumentTypeBinding::Wrap)
     }
 }
 

src/components/script/dom/domexception.rs

@@ -3,12 +3,13 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::DOMExceptionBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::window::Window;
 use servo_util::str::DOMString;
 
 #[repr(uint)]
-#[deriving(ToStr)]
+#[deriving(ToStr, Encodable)]
 enum DOMErrorName {
     IndexSizeError = 1,
     HierarchyRequestError = 3,
@@ -33,6 +34,7 @@ enum DOMErrorName {
     EncodingError
 }
 
+#[deriving(Encodable)]
 pub struct DOMException {
     code: DOMErrorName,
     reflector_: Reflector
@@ -46,8 +48,8 @@ impl DOMException {
         }
     }
 
-    pub fn new(window: &Window, code: DOMErrorName) -> @mut DOMException {
-        reflect_dom_object(@mut DOMException::new_inherited(code), window, DOMExceptionBinding::Wrap)
+    pub fn new(window: &Window, code: DOMErrorName) -> JS<DOMException> {
+        reflect_dom_object(~DOMException::new_inherited(code), window, DOMExceptionBinding::Wrap)
     }
 }
 
@@ -67,7 +69,7 @@ impl DOMException {
         match self.code {
             // http://dom.spec.whatwg.org/#concept-throw
             EncodingError => 0,
-            _ => self.code as u16
+            code => code as u16
         }
     }
 

src/components/script/dom/domimplementation.rs

@@ -3,36 +3,39 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::DOMImplementationBinding;
+use dom::bindings::codegen::InheritTypes::{NodeCast, DocumentCast};
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflector, Reflectable, reflect_dom_object};
 use dom::bindings::utils::{Fallible, InvalidCharacter, NamespaceError};
 use dom::bindings::utils::{QName, Name, InvalidXMLName, xml_name_type};
-use dom::document::{AbstractDocument, HTML, HTMLDocumentTypeId};
+use dom::document::{Document, HTML, HTMLDocumentTypeId};
 use dom::documenttype::DocumentType;
 use dom::htmldocument::HTMLDocument;
 use dom::htmlbodyelement::HTMLBodyElement;
 use dom::htmlheadelement::HTMLHeadElement;
 use dom::htmlhtmlelement::HTMLHtmlElement;
 use dom::htmltitleelement::HTMLTitleElement;
-use dom::node::{AbstractNode, DocumentNodeTypeId};
+use dom::node::{Node, DocumentNodeTypeId, NodeHelpers, INode};
 use dom::text::Text;
 use dom::window::Window;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct DOMImplementation {
-    owner: @mut Window,
-    reflector_: Reflector
+    owner: JS<Window>,
+    reflector_: Reflector,
 }
 
 impl DOMImplementation {
-    pub fn new_inherited(owner: @mut Window) -> DOMImplementation {
+    pub fn new_inherited(owner: JS<Window>) -> DOMImplementation {
         DOMImplementation {
             owner: owner,
-            reflector_: Reflector::new()
+            reflector_: Reflector::new(),
         }
     }
 
-    pub fn new(owner: @mut Window) -> @mut DOMImplementation {
-        reflect_dom_object(@mut DOMImplementation::new_inherited(owner), owner,
+    pub fn new(owner: &JS<Window>) -> JS<DOMImplementation> {
+        reflect_dom_object(~DOMImplementation::new_inherited(owner.clone()), owner.get(),
                            DOMImplementationBinding::Wrap)
     }
 }
@@ -50,66 +53,66 @@ impl Reflectable for DOMImplementation {
 // http://dom.spec.whatwg.org/#domimplementation
 impl DOMImplementation {
     // http://dom.spec.whatwg.org/#dom-domimplementation-createdocumenttype
-    pub fn CreateDocumentType(&self, qname: DOMString, pubid: DOMString, sysid: DOMString) -> Fallible<AbstractNode> {
+    pub fn CreateDocumentType(&self, qname: DOMString, pubid: DOMString, sysid: DOMString) -> Fallible<JS<DocumentType>> {
         match xml_name_type(qname) {
             // Step 1.
             InvalidXMLName => Err(InvalidCharacter),
             // Step 2.
             Name => Err(NamespaceError),
             // Step 3.
-            QName => Ok(DocumentType::new(qname, Some(pubid), Some(sysid), self.owner.Document()))
+            QName => Ok(DocumentType::new(qname, Some(pubid), Some(sysid), &self.owner.get().Document()))
         }
     }
 
     // http://dom.spec.whatwg.org/#dom-domimplementation-createhtmldocument
-    pub fn CreateHTMLDocument(&self, title: Option<DOMString>) -> AbstractDocument {
+    pub fn CreateHTMLDocument(&self, title: Option<DOMString>) -> JS<Document> {
         // Step 1-2.
-        let abstract_doc = HTMLDocument::new(self.owner, None);
-        assert!(abstract_doc.document().doctype == HTML);
+        let doc: JS<Document> = DocumentCast::from(&HTMLDocument::new(&self.owner, None));
+        assert!(doc.get().doctype == HTML);
 
-        let abstract_node = AbstractNode::from_document(abstract_doc);
-        assert!(abstract_node.type_id() == DocumentNodeTypeId(HTMLDocumentTypeId));
+        let mut doc_node: JS<Node> = NodeCast::from(&doc);
+        assert!(doc_node.type_id() == DocumentNodeTypeId(HTMLDocumentTypeId));
 
         {
             // Step 3.
-            let doc_type = DocumentType::new(~"html", None, None, abstract_doc);
-            abstract_node.AppendChild(doc_type);
+            let doc_type = DocumentType::new(~"html", None, None, &doc);
+            doc_node.AppendChild(&mut NodeCast::from(&doc_type));
         }
 
         {
             // Step 4.
-            let doc_html = HTMLHtmlElement::new(~"html", abstract_doc);
-            abstract_node.AppendChild(doc_html);
+            let mut doc_html = NodeCast::from(&HTMLHtmlElement::new(~"html", &doc));
+            doc_node.AppendChild(&mut doc_html);
 
             {
                 // Step 5.
-                let doc_head = HTMLHeadElement::new(~"head", abstract_doc);
-                doc_html.AppendChild(doc_head);
+                let mut doc_head = NodeCast::from(&HTMLHeadElement::new(~"head", &doc));
+                doc_html.AppendChild(&mut doc_head);
 
                 // Step 6.
                 match title {
                     None => (),
                     Some(title_str) => {
                         // Step 6.1.
-                        let doc_title = HTMLTitleElement::new(~"title", abstract_doc);
-                        doc_head.AppendChild(doc_title);
+                        let mut doc_title = NodeCast::from(&HTMLTitleElement::new(~"title", &doc));
+                        doc_head.AppendChild(&mut doc_title);
 
                         // Step 6.2.
-                        let title_text = Text::new(title_str, abstract_doc);
-                        doc_title.AppendChild(title_text);
+                        let title_text = Text::new(title_str, &doc);
+                        doc_title.AppendChild(&mut NodeCast::from(&title_text));
                     }
                 }
             }
 
             // Step 7.
-            let doc_body = HTMLBodyElement::new(~"body", abstract_doc);
-            doc_html.AppendChild(doc_body);
+            let doc_body = HTMLBodyElement::new(~"body", &doc);
+            doc_html.AppendChild(&mut NodeCast::from(&doc_body));
         }
 
         // Step 8.
         // FIXME: https://github.com/mozilla/servo/issues/1522
 
         // Step 9.
-        abstract_doc
+        doc
     }
 }

src/components/script/dom/domparser.rs

@@ -4,46 +4,49 @@
 
 use dom::bindings::codegen::DOMParserBinding;
 use dom::bindings::codegen::DOMParserBinding::SupportedTypeValues::{Text_html, Text_xml};
+use dom::bindings::codegen::InheritTypes::DocumentCast;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflector, Reflectable, reflect_dom_object};
 use dom::bindings::utils::Fallible;
 use dom::bindings::utils::FailureUnknown;
-use dom::document::{AbstractDocument, Document};
+use dom::document::Document;
 use dom::htmldocument::HTMLDocument;
 use dom::window::Window;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct DOMParser {
-    owner: @mut Window, //XXXjdm Document instead?
+    owner: JS<Window>, //XXXjdm Document instead?
     reflector_: Reflector
 }
 
 impl DOMParser {
-    pub fn new_inherited(owner: @mut Window) -> DOMParser {
+    pub fn new_inherited(owner: JS<Window>) -> DOMParser {
         DOMParser {
             owner: owner,
             reflector_: Reflector::new()
         }
     }
 
-    pub fn new(owner: @mut Window) -> @mut DOMParser {
-        reflect_dom_object(@mut DOMParser::new_inherited(owner), owner,
+    pub fn new(owner: &JS<Window>) -> JS<DOMParser> {
+        reflect_dom_object(~DOMParser::new_inherited(owner.clone()), owner.get(),
                            DOMParserBinding::Wrap)
     }
 
-    pub fn Constructor(owner: @mut Window) -> Fallible<@mut DOMParser> {
+    pub fn Constructor(owner: &JS<Window>) -> Fallible<JS<DOMParser>> {
         Ok(DOMParser::new(owner))
     }
 
     pub fn ParseFromString(&self,
                            _s: DOMString,
                            ty: DOMParserBinding::SupportedType)
-                           -> Fallible<AbstractDocument> {
+                           -> Fallible<JS<Document>> {
         match ty {
             Text_html => {
-                Ok(HTMLDocument::new(self.owner, None))
+                Ok(DocumentCast::from(&HTMLDocument::new(&self.owner, None)))
             }
             Text_xml => {
-                Document::Constructor(self.owner)
+                Document::Constructor(&self.owner)
             }
             _ => {
                 Err(FailureUnknown)

src/components/script/dom/element.rs

@@ -6,14 +6,22 @@
 
 use dom::attr::Attr;
 use dom::attrlist::AttrList;
+use dom::bindings::codegen::InheritTypes::{ElementDerived, HTMLImageElementCast};
+use dom::bindings::codegen::InheritTypes::{HTMLIFrameElementCast, NodeCast};
+use dom::bindings::codegen::InheritTypes::HTMLObjectElementCast;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::bindings::utils::{ErrorResult, Fallible, NamespaceError, InvalidCharacter};
 use dom::bindings::utils::{QName, Name, InvalidXMLName, xml_name_type};
 use dom::htmlcollection::HTMLCollection;
 use dom::clientrect::ClientRect;
 use dom::clientrectlist::ClientRectList;
-use dom::document::AbstractDocument;
-use dom::node::{AbstractNode, ElementNodeTypeId, Node, NodeIterator};
+use dom::document::Document;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::htmlimageelement::HTMLImageElement;
+use dom::htmliframeelement::HTMLIFrameElement;
+use dom::htmlobjectelement::HTMLObjectElement;
+use dom::node::{ElementNodeTypeId, Node, NodeHelpers, NodeIterator};
 use dom::document;
 use dom::htmlserializer::serialize;
 use layout_interface::{ContentBoxQuery, ContentBoxResponse, ContentBoxesQuery};
@@ -26,15 +34,24 @@ use servo_util::str::{DOMString, null_str_as_empty_ref};
 
 use std::ascii::StrAsciiExt;
 use std::cast;
-use std::unstable::raw::Box;
 
+#[deriving(Encodable)]
 pub struct Element {
     node: Node,
     tag_name: DOMString,     // TODO: This should be an atom, not a DOMString.
     namespace: Namespace,
-    attrs: ~[@mut Attr],
+    attrs: ~[JS<Attr>],
     style_attribute: Option<style::PropertyDeclarationBlock>,
-    attr_list: Option<@mut AttrList>
+    attr_list: Option<JS<AttrList>>
+}
+
+impl ElementDerived for EventTarget {
+    fn is_element(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(_)) => true,
+            _ => false
+        }
+    }
 }
 
 impl Reflectable for Element {
@@ -47,7 +64,7 @@ impl Reflectable for Element {
     }
 }
 
-#[deriving(Eq)]
+#[deriving(Eq,Encodable)]
 pub enum ElementTypeId {
     HTMLElementTypeId,
     HTMLAnchorElementTypeId,
@@ -104,7 +121,6 @@ pub enum ElementTypeId {
     HTMLStyleElementTypeId,
     HTMLTableElementTypeId,
     HTMLTableCaptionElementTypeId,
-    HTMLTableCellElementTypeId,
     HTMLTableDataCellElementTypeId,
     HTMLTableHeaderCellElementTypeId,
     HTMLTableColElementTypeId,
@@ -124,9 +140,8 @@ pub enum ElementTypeId {
 // Element methods
 //
 
-
 impl Element {
-    pub fn new_inherited(type_id: ElementTypeId, tag_name: ~str, namespace: Namespace, document: AbstractDocument) -> Element {
+    pub fn new_inherited(type_id: ElementTypeId, tag_name: ~str, namespace: Namespace, document: JS<Document>) -> Element {
         Element {
             node: Node::new_inherited(ElementNodeTypeId(type_id), document),
             tag_name: tag_name,
@@ -141,38 +156,39 @@ impl Element {
         let owner = self.node.owner_doc();
         self.namespace == namespace::HTML &&
         // FIXME: check that this matches what the spec calls "is in an HTML document"
-        owner.document().doctype == document::HTML
+        owner.get().doctype == document::HTML
     }
 
     pub fn get_attribute(&self,
                          namespace: Namespace,
-                         name: &str) -> Option<@mut Attr> {
+                         name: &str) -> Option<JS<Attr>> {
         self.attrs.iter().find(|attr| {
+            let attr = attr.get();
             name == attr.local_name && attr.namespace == namespace
-        }).map(|&x| x)
+        }).map(|x| x.clone())
     }
 
     #[inline]
     pub unsafe fn get_attr_val_for_layout(&self, namespace: &Namespace, name: &str)
                                           -> Option<&'static str> {
-        self.attrs.iter().find(|attr: & &@mut Attr| {
+        self.attrs.iter().find(|attr: & &JS<Attr>| {
             // unsafely avoid a borrow because this is accessed by many tasks
             // during parallel layout
-            let attr: ***Box<Attr> = cast::transmute(attr);
-            name == (***attr).data.local_name && (***attr).data.namespace == *namespace
+            let attr: ***Attr = cast::transmute(attr);
+            name == (***attr).local_name && (***attr).namespace == *namespace
        }).map(|attr| {
-            let attr: **Box<Attr> = cast::transmute(attr);
-            cast::transmute((**attr).data.value.as_slice())
+            let attr: **Attr = cast::transmute(attr);
+            cast::transmute((**attr).value.as_slice())
         })
     }
 
-    pub fn set_attr(&mut self, abstract_self: AbstractNode, name: DOMString, value: DOMString)
+    pub fn set_attr(&mut self, abstract_self: &JS<Element>, name: DOMString, value: DOMString)
                     -> ErrorResult {
         self.set_attribute(abstract_self, namespace::Null, name, value)
     }
 
     pub fn set_attribute(&mut self,
-                         abstract_self: AbstractNode,
+                         abstract_self: &JS<Element>,
                          namespace: Namespace,
                          name: DOMString,
                          value: DOMString) -> ErrorResult {
@@ -192,7 +208,8 @@ impl Element {
 
         // FIXME: reduce the time of `value.clone()`.
         let mut old_raw_value: Option<DOMString> = None;
-        for attr in self.attrs.iter() {
+        for attr in self.attrs.mut_iter() {
+            let attr = attr.get_mut();
             if attr.local_name == local_name {
                 old_raw_value = Some(attr.set_value(value.clone()));
                 break;
@@ -200,8 +217,9 @@ impl Element {
         }
 
         if old_raw_value.is_none() {
-            let win = self.node.owner_doc().document().window;
-            let new_attr = Attr::new_ns(win, local_name.clone(), value.clone(),
+            let doc = self.node.owner_doc();
+            let doc = doc.get();
+            let new_attr = Attr::new_ns(doc.window.get(), local_name.clone(), value.clone(),
                                         name.clone(), namespace.clone(),
                                         prefix);
             self.attrs.push(new_attr);
@@ -214,7 +232,7 @@ impl Element {
     }
 
     fn after_set_attr(&mut self,
-                      abstract_self: AbstractNode,
+                      abstract_self: &JS<Element>,
                       local_name: DOMString,
                       value: DOMString,
                       old_value: Option<DOMString>) {
@@ -222,36 +240,36 @@ impl Element {
         match local_name.as_slice() {
             "style" => {
                 let doc = self.node.owner_doc();
-                let base_url = doc.document().url.clone();
+                let base_url = doc.get().extra.url.clone();
                 self.style_attribute = Some(style::parse_style_attribute(value, &base_url))
             }
-            "id" if abstract_self.is_in_doc() => {
+            "id" => {
+                let self_node: JS<Node> = NodeCast::from(abstract_self);
+                if self_node.is_in_doc() {
                     // XXX: this dual declaration are workaround to avoid the compile error:
                     // "borrowed value does not live long enough"
-                let doc = self.node.owner_doc();
-                let doc = doc.mut_document();
+                    let mut doc = self.node.owner_doc();
+                    let doc = doc.get_mut();
                     doc.update_idmap(abstract_self, Some(value.clone()), old_value);
                 }
+            }
             _ => ()
         }
 
         //XXXjdm We really need something like a vtable so we can call AfterSetAttr.
         //       This hardcoding is awful.
-        match abstract_self.type_id() {
+        match abstract_self.get().node.type_id {
             ElementNodeTypeId(HTMLImageElementTypeId) => {
-                abstract_self.with_mut_image_element(|image| {
-                    image.AfterSetAttr(local_name.clone(), value.clone());
-                });
+                let mut elem: JS<HTMLImageElement> = HTMLImageElementCast::to(abstract_self);
+                elem.get_mut().AfterSetAttr(local_name.clone(), value.clone());
             }
             ElementNodeTypeId(HTMLIframeElementTypeId) => {
-                abstract_self.with_mut_iframe_element(|iframe| {
-                    iframe.AfterSetAttr(local_name.clone(), value.clone());
-                });
+                let mut elem: JS<HTMLIFrameElement> = HTMLIFrameElementCast::to(abstract_self);
+                elem.get_mut().AfterSetAttr(local_name.clone(), value.clone());
             }
             ElementNodeTypeId(HTMLObjectElementTypeId) => {
-                abstract_self.with_mut_object_element(|object| {
-                    object.AfterSetAttr(local_name.clone(), value.clone());
-                });
+                let mut elem: JS<HTMLObjectElement> = HTMLObjectElementCast::to(abstract_self);
+                elem.get_mut().AfterSetAttr(local_name.clone(), value.clone());
             }
             _ => ()
         }
@@ -260,22 +278,22 @@ impl Element {
     }
 
     pub fn remove_attribute(&mut self,
-                            abstract_self: AbstractNode,
+                            abstract_self: &JS<Element>,
                             namespace: Namespace,
                             name: DOMString) -> ErrorResult {
         let (_, local_name) = get_attribute_parts(name.clone());
 
         self.node.wait_until_safe_to_modify_dom();
 
-        let idx = self.attrs.iter().position(|attr: &@mut Attr| -> bool {
-            attr.local_name == local_name
+        let idx = self.attrs.iter().position(|attr: &JS<Attr>| -> bool {
+            attr.get().local_name == local_name
         });
 
         match idx {
             None => (),
             Some(idx) => {
                 let removed = self.attrs.remove(idx);
-                let removed_raw_value = Some(removed.Value());
+                let removed_raw_value = Some(removed.get().Value());
 
                 if namespace == namespace::Null {
                     self.after_remove_attr(abstract_self, local_name, removed_raw_value);
@@ -287,35 +305,36 @@ impl Element {
     }
 
     fn after_remove_attr(&mut self,
-                         abstract_self: AbstractNode,
+                         abstract_self: &JS<Element>,
                          local_name: DOMString,
                          old_value: Option<DOMString>) {
         match local_name.as_slice() {
             "style" => {
                 self.style_attribute = None
             }
-            "id" if abstract_self.is_in_doc() => {
+            "id" => {
+                let self_node: JS<Node> = NodeCast::from(abstract_self);
+                if self_node.is_in_doc() {
                     // XXX: this dual declaration are workaround to avoid the compile error:
                     // "borrowed value does not live long enough"
-                let doc = self.node.owner_doc();
-                let doc = doc.mut_document();
+                    let mut doc = self.node.owner_doc();
+                    let doc = doc.get_mut();
                     doc.update_idmap(abstract_self, None, old_value);
                 }
+            }
             _ => ()
         }
 
         //XXXjdm We really need something like a vtable so we can call AfterSetAttr.
         //       This hardcoding is awful.
-        match abstract_self.type_id() {
+        match abstract_self.get().node.type_id {
             ElementNodeTypeId(HTMLImageElementTypeId) => {
-                abstract_self.with_mut_image_element(|image| {
-                    image.AfterRemoveAttr(local_name.clone());
-                });
+                let mut elem: JS<HTMLImageElement> = HTMLImageElementCast::to(abstract_self);
+                elem.get_mut().AfterRemoveAttr(local_name.clone());
             }
             ElementNodeTypeId(HTMLIframeElementTypeId) => {
-                abstract_self.with_mut_iframe_element(|iframe| {
-                    iframe.AfterRemoveAttr(local_name.clone());
-                });
+                let mut elem: JS<HTMLIFrameElement> = HTMLIFrameElementCast::to(abstract_self);
+                elem.get_mut().AfterRemoveAttr(local_name.clone());
             }
             _ => ()
         }
@@ -324,15 +343,16 @@ impl Element {
     }
 
     fn notify_attribute_changed(&self,
-                                abstract_self: AbstractNode,
+                                abstract_self: &JS<Element>,
                                 local_name: DOMString) {
-        if abstract_self.is_in_doc() {
+        let node: JS<Node> = NodeCast::from(abstract_self);
+        if node.is_in_doc() {
             let damage = match local_name.as_slice() {
                 "style" | "id" | "class" => MatchSelectorsDocumentDamage,
                 _ => ContentChangedDocumentDamage
             };
             let document = self.node.owner_doc();
-            document.document().damage_and_reflow(damage);
+            document.get().damage_and_reflow(damage);
         }
     }
 
@@ -357,18 +377,18 @@ impl Element {
         // XXX Resolve URL.
         self.get_string_attribute(name)
     }
-    pub fn set_url_attribute(&mut self, abstract_self: AbstractNode,
+    pub fn set_url_attribute(&mut self, abstract_self: &JS<Element>,
                              name: &str, value: DOMString) {
         self.set_string_attribute(abstract_self, name, value);
     }
 
     pub fn get_string_attribute(&self, name: &str) -> DOMString {
         match self.get_attribute(Null, name) {
-            Some(x) => x.Value(),
+            Some(x) => x.get().Value(),
             None => ~""
         }
     }
-    pub fn set_string_attribute(&mut self, abstract_self: AbstractNode,
+    pub fn set_string_attribute(&mut self, abstract_self: &JS<Element>,
                                 name: &str, value: DOMString) {
         assert!(name == name.to_ascii_lower());
         self.set_attribute(abstract_self, Null, name.to_owned(), value);
@@ -382,25 +402,26 @@ impl Element {
     }
 
     // http://dom.spec.whatwg.org/#dom-element-id
-    pub fn Id(&self, _abstract_self: AbstractNode) -> DOMString {
+    pub fn Id(&self, _abstract_self: &JS<Element>) -> DOMString {
         self.get_string_attribute("id")
     }
 
     // http://dom.spec.whatwg.org/#dom-element-id
-    pub fn SetId(&mut self, abstract_self: AbstractNode, id: DOMString) {
+    pub fn SetId(&mut self, abstract_self: &JS<Element>, id: DOMString) {
         self.set_string_attribute(abstract_self, "id", id);
     }
 
     // http://dom.spec.whatwg.org/#dom-element-attributes
-    pub fn Attributes(&mut self, abstract_self: AbstractNode) -> @mut AttrList {
+    pub fn Attributes(&mut self, abstract_self: &JS<Element>) -> JS<AttrList> {
         match self.attr_list {
             None => {
-                let window = self.node.owner_doc().document().window;
-                let list = AttrList::new(window, abstract_self);
-                self.attr_list = Some(list);
+                let doc = self.node.owner_doc();
+                let doc = doc.get();
+                let list = AttrList::new(&doc.window, abstract_self);
+                self.attr_list = Some(list.clone());
                 list
             }
-            Some(list) => list
+            Some(ref list) => list.clone()
         }
     }
 
@@ -411,18 +432,18 @@ impl Element {
         } else {
             name
         };
-        self.get_attribute(Null, name).map(|s| s.Value())
+        self.get_attribute(Null, name).map(|s| s.get().Value())
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getattributens
     pub fn GetAttributeNS(&self, namespace: Option<DOMString>, local_name: DOMString) -> Option<DOMString> {
         let namespace = Namespace::from_str(null_str_as_empty_ref(&namespace));
         self.get_attribute(namespace, local_name)
-            .map(|attr| attr.value.clone())
+            .map(|attr| attr.get().value.clone())
     }
 
     // http://dom.spec.whatwg.org/#dom-element-setattribute
-    pub fn SetAttribute(&mut self, abstract_self: AbstractNode, name: DOMString, value: DOMString)
+    pub fn SetAttribute(&mut self, abstract_self: &JS<Element>, name: DOMString, value: DOMString)
                         -> ErrorResult {
         // FIXME: If name does not match the Name production in XML, throw an "InvalidCharacterError" exception.
         let name = if self.html_element_in_html_document() {
@@ -435,7 +456,7 @@ impl Element {
 
     // http://dom.spec.whatwg.org/#dom-element-setattributens
     pub fn SetAttributeNS(&mut self,
-                          abstract_self: AbstractNode,
+                          abstract_self: &JS<Element>,
                           namespace_url: Option<DOMString>,
                           name: DOMString,
                           value: DOMString) -> ErrorResult {
@@ -452,7 +473,7 @@ impl Element {
 
     // http://dom.spec.whatwg.org/#dom-element-removeattribute
     pub fn RemoveAttribute(&mut self,
-                           abstract_self: AbstractNode,
+                           abstract_self: &JS<Element>,
                            name: DOMString) -> ErrorResult {
         let name = if self.html_element_in_html_document() {
             name.to_ascii_lower()
@@ -464,7 +485,7 @@ impl Element {
 
     // http://dom.spec.whatwg.org/#dom-element-removeattributens
     pub fn RemoveAttributeNS(&mut self,
-                             abstract_self: AbstractNode,
+                             abstract_self: &JS<Element>,
                              namespace: Option<DOMString>,
                              localname: DOMString) -> ErrorResult {
         let namespace = Namespace::from_str(null_str_as_empty_ref(&namespace));
@@ -482,21 +503,24 @@ impl Element {
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getelementsbytagname
-    pub fn GetElementsByTagName(&self, _localname: DOMString) -> @mut HTMLCollection {
+    pub fn GetElementsByTagName(&self, _localname: DOMString) -> JS<HTMLCollection> {
         // FIXME: stub - https://github.com/mozilla/servo/issues/1660
-        HTMLCollection::new(self.node.owner_doc().document().window, ~[])
+        let doc = self.node.owner_doc();
+        HTMLCollection::new(&doc.get().window, ~[])
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getelementsbytagnamens
-    pub fn GetElementsByTagNameNS(&self, _namespace: Option<DOMString>, _localname: DOMString) -> Fallible<@mut HTMLCollection> {
+    pub fn GetElementsByTagNameNS(&self, _namespace: Option<DOMString>, _localname: DOMString) -> Fallible<JS<HTMLCollection>> {
         // FIXME: stub - https://github.com/mozilla/servo/issues/1660
-        Ok(HTMLCollection::new(self.node.owner_doc().document().window, ~[]))
+        let doc = self.node.owner_doc();
+        Ok(HTMLCollection::new(&doc.get().window, ~[]))
     }
 
     // http://dom.spec.whatwg.org/#dom-element-getelementsbyclassname
-    pub fn GetElementsByClassName(&self, _names: DOMString) -> @mut HTMLCollection {
+    pub fn GetElementsByClassName(&self, _names: DOMString) -> JS<HTMLCollection> {
         // FIXME: stub - https://github.com/mozilla/servo/issues/1660
-        HTMLCollection::new(self.node.owner_doc().document().window, ~[])
+        let doc = self.node.owner_doc();
+        HTMLCollection::new(&doc.get().window, ~[])
     }
 
     // http://dom.spec.whatwg.org/#dom-element-matches
@@ -517,13 +541,14 @@ impl Element {
     pub fn MozRequestPointerLock(&self) {
     }
 
-    pub fn GetClientRects(&self, abstract_self: AbstractNode) -> @mut ClientRectList {
-        let win = self.node.owner_doc().document().window;
-        let node = abstract_self;
-        assert!(node.is_element());
+    pub fn GetClientRects(&self, abstract_self: &JS<Element>) -> JS<ClientRectList> {
+        let doc = self.node.owner_doc();
+        let win = &doc.get().window;
+        let node: JS<Node> = NodeCast::from(abstract_self);
         let (port, chan) = Chan::new();
+        let addr = node.to_trusted_node_address();
         let rects =
-            match win.page.query_layout(ContentBoxesQuery(node, chan), port) {
+            match win.get().page.query_layout(ContentBoxesQuery(addr, chan), port) {
                 ContentBoxesResponse(rects) => {
                     rects.map(|r| {
                         ClientRect::new(
@@ -539,12 +564,13 @@ impl Element {
         ClientRectList::new(win, rects)
     }
 
-    pub fn GetBoundingClientRect(&self, abstract_self: AbstractNode) -> @mut ClientRect {
-        let win = self.node.owner_doc().document().window;
-        let node = abstract_self;
-        assert!(node.is_element());
+    pub fn GetBoundingClientRect(&self, abstract_self: &JS<Element>) -> JS<ClientRect> {
+        let doc = self.node.owner_doc();
+        let win = &doc.get().window;
+        let node: JS<Node> = NodeCast::from(abstract_self);
         let (port, chan) = Chan::new();
-        match win.page.query_layout(ContentBoxQuery(node, chan), port) {
+        let addr = node.to_trusted_node_address();
+        match win.get().page.query_layout(ContentBoxQuery(addr, chan), port) {
             ContentBoxResponse(rect) => {
                 ClientRect::new(
                     win,
@@ -597,20 +623,20 @@ impl Element {
         0
     }
 
-    pub fn GetInnerHTML(&self, abstract_self: AbstractNode) -> Fallible<DOMString> {
+    pub fn GetInnerHTML(&self, abstract_self: &JS<Element>) -> Fallible<DOMString> {
         //XXX TODO: XML case
-        Ok(serialize(&mut NodeIterator::new(abstract_self, false, false)))
+        Ok(serialize(&mut NodeIterator::new(NodeCast::from(abstract_self), false, false)))
     }
 
-    pub fn SetInnerHTML(&mut self, _abstract_self: AbstractNode, _value: DOMString) -> ErrorResult {
+    pub fn SetInnerHTML(&mut self, _abstract_self: &JS<Element>, _value: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn GetOuterHTML(&self, abstract_self:AbstractNode) -> Fallible<DOMString> {
-        Ok(serialize(&mut NodeIterator::new(abstract_self, true, false)))
+    pub fn GetOuterHTML(&self, abstract_self: &JS<Element>) -> Fallible<DOMString> {
+        Ok(serialize(&mut NodeIterator::new(NodeCast::from(abstract_self), true, false)))
     }
 
-    pub fn SetOuterHTML(&mut self, _abstract_self: AbstractNode, _value: DOMString) -> ErrorResult {
+    pub fn SetOuterHTML(&mut self, _abstract_self: &JS<Element>, _value: DOMString) -> ErrorResult {
         Ok(())
     }
 
@@ -618,7 +644,7 @@ impl Element {
         Ok(())
     }
 
-    pub fn QuerySelector(&self, _selectors: DOMString) -> Fallible<Option<AbstractNode>> {
+    pub fn QuerySelector(&self, _selectors: DOMString) -> Fallible<Option<JS<Element>>> {
         Ok(None)
     }
 }

src/components/script/dom/event.rs

@@ -2,20 +2,16 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use dom::eventtarget::AbstractEventTarget;
-use dom::window::Window;
 use dom::bindings::codegen::EventBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::utils::{Fallible, ErrorResult};
-use dom::mouseevent::MouseEvent;
-use dom::uievent::UIEvent;
+use dom::eventtarget::EventTarget;
+use dom::window::Window;
 use servo_util::str::DOMString;
 
 use geom::point::Point2D;
 
-use std::cast;
-use std::unstable::raw::Box;
-
 pub enum Event_ {
     ResizeEvent(uint, uint), 
     ReflowEvent,
@@ -25,10 +21,7 @@ pub enum Event_ {
     MouseMoveEvent(Point2D<f32>)
 }
 
-pub struct AbstractEvent {
-    event: *mut Box<Event>
-}
-
+#[deriving(Encodable)]
 pub enum EventPhase {
     Phase_None = 0,
     Phase_Capturing,
@@ -36,91 +29,7 @@ pub enum EventPhase {
     Phase_Bubbling
 }
 
-impl AbstractEvent {
-    pub fn from_box(box_: *mut Box<Event>) -> AbstractEvent {
-        AbstractEvent {
-            event: box_
-        }
-    }
-
-    //
-    // Downcasting borrows
-    //
-
-    fn transmute<'a, T>(&'a self) -> &'a T {
-        unsafe {
-            let box_: *Box<T> = self.event as *Box<T>;
-            &(*box_).data
-        }
-    }
-
-    fn transmute_mut<'a, T>(&'a self) -> &'a mut T {
-        unsafe {
-            let box_: *mut Box<T> = self.event as *mut Box<T>;
-            &mut (*box_).data
-        }
-    }
-
-    pub fn type_id(&self) -> EventTypeId {
-        self.event().type_id
-    }
-
-    pub fn event<'a>(&'a self) -> &'a Event {
-        self.transmute()
-    }
-
-    pub fn mut_event<'a>(&'a self) -> &'a mut Event {
-        self.transmute_mut()
-    }
-
-    pub fn is_uievent(&self) -> bool {
-        self.type_id() == UIEventTypeId
-    }
-
-    pub fn uievent<'a>(&'a self) -> &'a UIEvent {
-        assert!(self.is_uievent());
-        self.transmute()
-    }
-
-    pub fn mut_uievent<'a>(&'a self) -> &'a mut UIEvent {
-        assert!(self.is_uievent());
-        self.transmute_mut()
-    }
-
-    pub fn is_mouseevent(&self) -> bool {
-        self.type_id() == MouseEventTypeId
-    }
-
-    pub fn mouseevent<'a>(&'a self) -> &'a MouseEvent {
-        assert!(self.is_mouseevent());
-        self.transmute()
-    }
-
-    pub fn mut_mouseevent<'a>(&'a self) -> &'a mut MouseEvent {
-        assert!(self.is_mouseevent());
-        self.transmute_mut()
-    }
-
-    pub fn propagation_stopped(&self) -> bool {
-        self.event().stop_propagation
-    }
-
-    pub fn bubbles(&self) -> bool {
-        self.event().bubbles
-    }
-}
-
-impl Reflectable for AbstractEvent {
-    fn reflector<'a>(&'a self) -> &'a Reflector {
-        self.event().reflector()
-    }
-
-    fn mut_reflector<'a>(&'a mut self) -> &'a mut Reflector {
-        self.mut_event().mut_reflector()
-    }
-}
-
-#[deriving(Eq)]
+#[deriving(Eq, Encodable)]
 pub enum EventTypeId {
     HTMLEventTypeId,
     UIEventTypeId,
@@ -128,11 +37,12 @@ pub enum EventTypeId {
     KeyEventTypeId
 }
 
+#[deriving(Encodable)]
 pub struct Event {
     type_id: EventTypeId,
     reflector_: Reflector,
-    current_target: Option<AbstractEventTarget>,
-    target: Option<AbstractEventTarget>,
+    current_target: Option<JS<EventTarget>>,
+    target: Option<JS<EventTarget>>,
     type_: DOMString,
     phase: EventPhase,
     default_prevented: bool,
@@ -142,7 +52,7 @@ pub struct Event {
     bubbles: bool,
     trusted: bool,
     dispatching: bool,
-    initialized: bool
+    initialized: bool,
 }
 
 impl Event {
@@ -165,18 +75,10 @@ impl Event {
         }
     }
 
-    //FIXME: E should be bounded by some trait that is only implemented for Event types
-    pub fn as_abstract<E>(event: @mut E) -> AbstractEvent {
-        // This surrenders memory management of the event!
-        AbstractEvent {
-            event: unsafe { cast::transmute(event) },
-        }
-    }
-
-    pub fn new(window: @mut Window) -> AbstractEvent {
-        let ev = reflect_dom_object(@mut Event::new_inherited(HTMLEventTypeId),
-                                    window, EventBinding::Wrap);
-        Event::as_abstract(ev)
+    pub fn new(window: &JS<Window>) -> JS<Event> {
+        reflect_dom_object(~Event::new_inherited(HTMLEventTypeId),
+                           window.get(),
+                           EventBinding::Wrap)
     }
 
     pub fn EventPhase(&self) -> u16 {
@@ -187,12 +89,12 @@ impl Event {
         self.type_.clone()
     }
 
-    pub fn GetTarget(&self) -> Option<AbstractEventTarget> {
-        self.target
+    pub fn GetTarget(&self) -> Option<JS<EventTarget>> {
+        self.target.clone()
     }
 
-    pub fn GetCurrentTarget(&self) -> Option<AbstractEventTarget> {
-        self.current_target
+    pub fn GetCurrentTarget(&self) -> Option<JS<EventTarget>> {
+        self.current_target.clone()
     }
 
     pub fn DefaultPrevented(&self) -> bool {
@@ -241,11 +143,11 @@ impl Event {
         self.trusted
     }
 
-    pub fn Constructor(global: @mut Window,
+    pub fn Constructor(global: &JS<Window>,
                        type_: DOMString,
-                       init: &EventBinding::EventInit) -> Fallible<AbstractEvent> {
-        let ev = Event::new(global);
-        ev.mut_event().InitEvent(type_, init.bubbles, init.cancelable);
+                       init: &EventBinding::EventInit) -> Fallible<JS<Event>> {
+        let mut ev = Event::new(global);
+        ev.get_mut().InitEvent(type_, init.bubbles, init.cancelable);
         Ok(ev)
     }
 }

src/components/script/dom/eventdispatcher.rs

@@ -3,50 +3,57 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::callback::eReportExceptions;
-use dom::eventtarget::{AbstractEventTarget, Capturing, Bubbling};
-use dom::event::{AbstractEvent, Phase_At_Target, Phase_None, Phase_Bubbling, Phase_Capturing};
-use dom::node::AbstractNode;
+use dom::bindings::codegen::InheritTypes::{EventTargetCast, NodeCast, NodeDerived};
+use dom::bindings::js::JS;
+use dom::eventtarget::{Capturing, Bubbling, EventTarget};
+use dom::event::{Event, Phase_At_Target, Phase_None, Phase_Bubbling, Phase_Capturing};
+use dom::node::{Node, NodeHelpers};
 
 // See http://dom.spec.whatwg.org/#concept-event-dispatch for the full dispatch algorithm
-pub fn dispatch_event(target: AbstractEventTarget,
-                      pseudo_target: Option<AbstractEventTarget>,
-                      event: AbstractEvent) -> bool {
-    assert!(!event.event().dispatching);
+pub fn dispatch_event(target: &JS<EventTarget>,
+                      pseudo_target: Option<JS<EventTarget>>,
+                      event: &mut JS<Event>) -> bool {
+    assert!(!event.get().dispatching);
 
     {
-        let event = event.mut_event();
-        event.target = Some(pseudo_target.unwrap_or(target));
+        let event = event.get_mut();
+        event.target = match pseudo_target {
+            Some(pseudo_target) => Some(pseudo_target),
+            None => Some(target.clone())
+        };
         event.dispatching = true;
     }
 
-    let type_ = event.event().type_.clone();
+    let type_ = event.get().type_.clone();
     let mut chain = ~[];
 
     //TODO: no chain if not participating in a tree
-    if target.is_node() {
-        for ancestor in AbstractNode::from_eventtarget(target).ancestors() {
-            chain.push(AbstractEventTarget::from_node(ancestor));
+    if target.get().is_node() {
+        let target_node: JS<Node> = NodeCast::to(target);
+        for ancestor in target_node.ancestors() {
+            let ancestor_target: JS<EventTarget> = EventTargetCast::from(&ancestor);
+            chain.push(ancestor_target);
         }
     }
 
-    event.mut_event().phase = Phase_Capturing;
+    event.get_mut().phase = Phase_Capturing;
 
     //FIXME: The "callback this value" should be currentTarget
 
     /* capturing */
-    for &cur_target in chain.rev_iter() {
-        let stopped = match cur_target.eventtarget().get_listeners_for(type_, Capturing) {
+    for cur_target in chain.rev_iter() {
+        let stopped = match cur_target.get().get_listeners_for(type_, Capturing) {
             Some(listeners) => {
-                event.mut_event().current_target = Some(cur_target);
+                event.get_mut().current_target = Some(cur_target.clone());
                 for listener in listeners.iter() {
                     listener.HandleEvent__(event, eReportExceptions);
 
-                    if event.event().stop_immediate {
+                    if event.get().stop_immediate {
                         break;
                     }
                 }
 
-                event.propagation_stopped()
+                event.get().stop_propagation
             }
             None => false
         };
@@ -57,18 +64,18 @@ pub fn dispatch_event(target: AbstractEventTarget,
     }
 
     /* at target */
-    if !event.propagation_stopped() {
+    if !event.get().stop_propagation {
         {
-            let event = event.mut_event();
+            let event = event.get_mut();
             event.phase = Phase_At_Target;
-            event.current_target = Some(target);
+            event.current_target = Some(target.clone());
         }
 
-        let opt_listeners = target.eventtarget().get_listeners(type_);
+        let opt_listeners = target.get().get_listeners(type_);
         for listeners in opt_listeners.iter() {
             for listener in listeners.iter() {
                 listener.HandleEvent__(event, eReportExceptions);
-                if event.event().stop_immediate {
+                if event.get().stop_immediate {
                     break;
                 }
             }
@@ -76,22 +83,22 @@ pub fn dispatch_event(target: AbstractEventTarget,
     }
 
     /* bubbling */
-    if event.bubbles() && !event.propagation_stopped() {
-        event.mut_event().phase = Phase_Bubbling;
+    if event.get().bubbles && !event.get().stop_propagation {
+        event.get_mut().phase = Phase_Bubbling;
 
-        for &cur_target in chain.iter() {
-            let stopped = match cur_target.eventtarget().get_listeners_for(type_, Bubbling) {
+        for cur_target in chain.iter() {
+            let stopped = match cur_target.get().get_listeners_for(type_, Bubbling) {
                 Some(listeners) => {
-                    event.mut_event().current_target = Some(cur_target);
+                    event.get_mut().current_target = Some(cur_target.clone());
                     for listener in listeners.iter() {
                         listener.HandleEvent__(event, eReportExceptions);
 
-                        if event.event().stop_immediate {
+                        if event.get().stop_immediate {
                             break;
                         }
                     }
 
-                    event.propagation_stopped()
+                    event.get().stop_propagation
                 }
                 None => false
             };
@@ -101,7 +108,7 @@ pub fn dispatch_event(target: AbstractEventTarget,
         }
     }
 
-    let event = event.mut_event();
+    let event = event.get_mut();
     event.dispatching = false;
     event.phase = Phase_None;
     event.current_target = None;

src/components/script/dom/eventtarget.rs

@@ -2,122 +2,42 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::bindings::utils::{Fallible, InvalidState};
 use dom::bindings::codegen::EventListenerBinding::EventListener;
-use dom::document::AbstractDocument;
-use dom::event::AbstractEvent;
+use dom::event::Event;
 use dom::eventdispatcher::dispatch_event;
-use dom::node::AbstractNode;
-use dom::window::Window;
+use dom::node::NodeTypeId;
 use servo_util::str::DOMString;
 
-use std::cast;
 use std::hashmap::HashMap;
-use std::unstable::raw::Box;
 
-#[deriving(Eq)]
+#[deriving(Eq,Encodable)]
 pub enum ListenerPhase {
     Capturing,
     Bubbling,
 }
 
-#[deriving(Eq)]
+#[deriving(Eq,Encodable)]
 pub enum EventTargetTypeId {
     WindowTypeId,
-    NodeTypeId
+    NodeTargetTypeId(NodeTypeId)
 }
 
-#[deriving(Eq)]
+#[deriving(Eq,Encodable)]
 struct EventListenerEntry {
     phase: ListenerPhase,
     listener: EventListener
 }
 
+#[deriving(Encodable)]
 pub struct EventTarget {
     type_id: EventTargetTypeId,
     reflector_: Reflector,
     handlers: HashMap<DOMString, ~[EventListenerEntry]>,
 }
 
-pub struct AbstractEventTarget {
-    eventtarget: *mut Box<EventTarget>
-}
-
-impl AbstractEventTarget {
-    pub fn from_box<T>(box_: *mut Box<T>) -> AbstractEventTarget {
-        AbstractEventTarget {
-            eventtarget: box_ as *mut Box<EventTarget>
-        }
-    }
-
-    pub fn from_node(node: AbstractNode) -> AbstractEventTarget {
-        unsafe {
-            cast::transmute(node)
-        }
-    }
-
-    pub fn from_window(window: @mut Window) -> AbstractEventTarget {
-        AbstractEventTarget {
-            eventtarget: unsafe { cast::transmute(window) }
-        }
-    }
-
-    pub fn from_document(document: AbstractDocument) -> AbstractEventTarget {
-        unsafe {
-            cast::transmute(document)
-        }
-    }
-
-    pub fn type_id(&self) -> EventTargetTypeId {
-        self.eventtarget().type_id
-    }
-
-    pub fn is_window(&self) -> bool {
-        self.type_id() == WindowTypeId
-    }
-
-    pub fn is_node(&self) -> bool {
-        self.type_id() == NodeTypeId
-    }
-
-    //
-    // Downcasting borrows
-    //
-
-    fn transmute<'a, T>(&'a self) -> &'a T {
-        unsafe {
-            let box_: *Box<T> = self.eventtarget as *Box<T>;
-            &(*box_).data
-        }
-    }
-
-    fn transmute_mut<'a, T>(&'a mut self) -> &'a mut T {
-        unsafe {
-            let box_: *mut Box<T> = self.eventtarget as *mut Box<T>;
-            &mut (*box_).data
-        }
-    }
-
-    pub fn eventtarget<'a>(&'a self) -> &'a EventTarget {
-        self.transmute()
-    }
-
-    pub fn mut_eventtarget<'a>(&'a mut self) -> &'a mut EventTarget {
-        self.transmute_mut()
-    }
-}
-
-impl Reflectable for AbstractEventTarget {
-    fn reflector<'a>(&'a self) -> &'a Reflector {
-        self.eventtarget().reflector()
-    }
-
-    fn mut_reflector<'a>(&'a mut self) -> &'a mut Reflector {
-        self.mut_eventtarget().mut_reflector()
-    }
-}
-
 impl EventTarget {
     pub fn new_inherited(type_id: EventTargetTypeId) -> EventTarget {
         EventTarget {
@@ -178,15 +98,16 @@ impl EventTarget {
         }
     }
 
-    pub fn DispatchEvent(&self, abstract_self: AbstractEventTarget, event: AbstractEvent) -> Fallible<bool> {
+    pub fn DispatchEvent(&self, abstract_self: &JS<EventTarget>,
+                         event: &mut JS<Event>) -> Fallible<bool> {
         self.dispatch_event_with_target(abstract_self, None, event)
     }
 
     pub fn dispatch_event_with_target(&self,
-                                      abstract_self: AbstractEventTarget,
-                                      abstract_target: Option<AbstractEventTarget>,
-                                      event: AbstractEvent) -> Fallible<bool> {
-        if event.event().dispatching || !event.event().initialized {
+                                      abstract_self: &JS<EventTarget>,
+                                      abstract_target: Option<JS<EventTarget>>,
+                                      event: &mut JS<Event>) -> Fallible<bool> {
+        if event.get().dispatching || !event.get().initialized {
             return Err(InvalidState);
         }
         Ok(dispatch_event(abstract_self, abstract_target, event))

src/components/script/dom/formdata.rs

@@ -4,27 +4,30 @@
 
 use dom::bindings::utils::{Fallible, Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::codegen::FormDataBinding;
+use dom::bindings::js::JS;
 use dom::blob::Blob;
-use dom::node::AbstractNode;
+use dom::htmlformelement::HTMLFormElement;
 use dom::window::Window;
 use servo_util::str::DOMString;
 
 use std::hashmap::HashMap;
 
+#[deriving(Encodable)]
 enum FormDatum {
     StringData(DOMString),
-    BlobData { blob: @mut Blob, name: DOMString }
+    BlobData { blob: JS<Blob>, name: DOMString }
 }
 
+#[deriving(Encodable)]
 pub struct FormData {
     data: HashMap<DOMString, FormDatum>,
     reflector_: Reflector,
-    window: @mut Window,
-    form: Option<AbstractNode>
+    window: JS<Window>,
+    form: Option<JS<HTMLFormElement>>
 }
 
 impl FormData {
-    pub fn new_inherited(form: Option<AbstractNode>, window: @mut Window) -> FormData {
+    pub fn new_inherited(form: Option<JS<HTMLFormElement>>, window: JS<Window>) -> FormData {
         FormData {
             data: HashMap::new(),
             reflector_: Reflector::new(),
@@ -33,18 +36,18 @@ impl FormData {
         }
     }
 
-    pub fn new(form: Option<AbstractNode>, window: @mut Window) -> @mut FormData {
-        reflect_dom_object(@mut FormData::new_inherited(form, window), window, FormDataBinding::Wrap)
+    pub fn new(form: Option<JS<HTMLFormElement>>, window: &JS<Window>) -> JS<FormData> {
+        reflect_dom_object(~FormData::new_inherited(form, window.clone()), window.get(), FormDataBinding::Wrap)
     }
 
-    pub fn Constructor(window: @mut Window, form: Option<AbstractNode>)
-                       -> Fallible<@mut FormData> {
+    pub fn Constructor(window: &JS<Window>, form: Option<JS<HTMLFormElement>>)
+                       -> Fallible<JS<FormData>> {
         Ok(FormData::new(form, window))
     }
 
-    pub fn Append(&mut self, name: DOMString, value: @mut Blob, filename: Option<DOMString>) {
+    pub fn Append(&mut self, name: DOMString, value: &JS<Blob>, filename: Option<DOMString>) {
         let blob = BlobData {
-            blob: value,
+            blob: value.clone(),
             name: filename.unwrap_or(~"default")
         };
         self.data.insert(name.clone(), blob);

src/components/script/dom/htmlanchorelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLAnchorElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLAnchorElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLAnchorElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLAnchorElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLAnchorElementDerived for EventTarget {
+    fn is_htmlanchorelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLAnchorElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLAnchorElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLAnchorElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLAnchorElement {
         HTMLAnchorElement {
             htmlelement: HTMLElement::new_inherited(HTMLAnchorElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLAnchorElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLAnchorElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLAnchorElement> {
+        let element = HTMLAnchorElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLAnchorElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlappletelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLAppletElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLAppletElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLAppletElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLAppletElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLAppletElementDerived for EventTarget {
+    fn is_htmlappletelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLAppletElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLAppletElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLAppletElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLAppletElement {
         HTMLAppletElement {
             htmlelement: HTMLElement::new_inherited(HTMLAppletElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLAppletElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLAppletElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLAppletElement> {
+        let element = HTMLAppletElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLAppletElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlareaelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLAreaElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLAreaElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLAreaElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLAreaElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLAreaElementDerived for EventTarget {
+    fn is_htmlareaelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLAreaElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLAreaElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLAreaElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLAreaElement {
         HTMLAreaElement {
             htmlelement: HTMLElement::new_inherited(HTMLAreaElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLAreaElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLAreaElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLAreaElement> {
+        let element = HTMLAreaElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLAreaElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlaudioelement.rs

@@ -3,25 +3,38 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLAudioElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLAudioElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLAudioElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlmediaelement::HTMLMediaElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLAudioElement {
     htmlmediaelement: HTMLMediaElement
 }
 
+impl HTMLAudioElementDerived for EventTarget {
+    fn is_htmlaudioelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLAudioElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLAudioElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLAudioElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLAudioElement {
         HTMLAudioElement {
             htmlmediaelement: HTMLMediaElement::new_inherited(HTMLAudioElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLAudioElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLAudioElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLAudioElement> {
+        let element = HTMLAudioElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLAudioElementBinding::Wrap)
     }
 }

src/components/script/dom/htmlbaseelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLBaseElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLBaseElementDerived;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLBaseElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLBaseElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLBaseElementDerived for EventTarget {
+    fn is_htmlbaseelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLBaseElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLBaseElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLBaseElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLBaseElement {
         HTMLBaseElement {
             htmlelement: HTMLElement::new_inherited(HTMLBaseElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLBaseElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLBaseElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLBaseElement> {
+        let element = HTMLBaseElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLBaseElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlbodyelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLBodyElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLBodyElementDerived;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLBodyElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLBodyElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLBodyElementDerived for EventTarget {
+    fn is_htmlbodyelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLBodyElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLBodyElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLBodyElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLBodyElement {
         HTMLBodyElement {
             htmlelement: HTMLElement::new_inherited(HTMLBodyElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLBodyElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLBodyElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLBodyElement> {
+        let element = HTMLBodyElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLBodyElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlbrelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLBRElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLBRElementDerived;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLBRElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLBRElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLBRElementDerived for EventTarget {
+    fn is_htmlbrelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLBRElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLBRElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLBRElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLBRElement {
         HTMLBRElement {
             htmlelement: HTMLElement::new_inherited(HTMLBRElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLBRElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLBRElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLBRElement> {
+        let element = HTMLBRElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLBRElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlbuttonelement.rs

@@ -3,28 +3,42 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLButtonElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLButtonElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLButtonElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::htmlformelement::HTMLFormElement;
+use dom::node::{Node, ElementNodeTypeId};
 use dom::validitystate::ValidityState;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLButtonElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLButtonElementDerived for EventTarget {
+    fn is_htmlbuttonelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLButtonElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLButtonElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLButtonElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLButtonElement {
         HTMLButtonElement {
             htmlelement: HTMLElement::new_inherited(HTMLButtonElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLButtonElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLButtonElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLButtonElement> {
+        let element = HTMLButtonElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLButtonElementBinding::Wrap)
     }
 }
 
@@ -45,7 +59,7 @@ impl HTMLButtonElement {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 
@@ -120,12 +134,13 @@ impl HTMLButtonElement {
     pub fn SetWillValidate(&mut self, _will_validate: bool) {
     }
 
-    pub fn Validity(&self) -> @mut ValidityState {
-        let global = self.htmlelement.element.node.owner_doc().document().window;
-        ValidityState::new(global)
+    pub fn Validity(&self) -> JS<ValidityState> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        ValidityState::new(&doc.window)
     }
 
-    pub fn SetValidity(&mut self, _validity: @mut ValidityState) {
+    pub fn SetValidity(&mut self, _validity: JS<ValidityState>) {
     }
 
     pub fn ValidationMessage(&self) -> DOMString {

src/components/script/dom/htmlcanvaselement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLCanvasElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLCanvasElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{ErrorResult};
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLCanvasElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLCanvasElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLCanvasElementDerived for EventTarget {
+    fn is_htmlcanvaselement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLCanvasElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLCanvasElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLCanvasElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLCanvasElement {
         HTMLCanvasElement {
             htmlelement: HTMLElement::new_inherited(HTMLCanvasElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLCanvasElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLCanvasElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLCanvasElement> {
+        let element = HTMLCanvasElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLCanvasElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlcollection.rs

@@ -3,9 +3,10 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLCollectionBinding;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::bindings::utils::Fallible;
-use dom::node::AbstractNode;
+use dom::element::Element;
 use dom::window::Window;
 use servo_util::str::DOMString;
 
@@ -13,14 +14,15 @@ use js::jsapi::{JSObject, JSContext};
 
 use std::ptr;
 
+#[deriving(Encodable)]
 pub struct HTMLCollection {
-    elements: ~[AbstractNode],
+    elements: ~[JS<Element>],
     reflector_: Reflector,
-    window: @mut Window,
+    window: JS<Window>,
 }
 
 impl HTMLCollection {
-    pub fn new_inherited(window: @mut Window, elements: ~[AbstractNode]) -> HTMLCollection {
+    pub fn new_inherited(window: JS<Window>, elements: ~[JS<Element>]) -> HTMLCollection {
         HTMLCollection {
             elements: elements,
             reflector_: Reflector::new(),
@@ -28,18 +30,18 @@ impl HTMLCollection {
         }
     }
 
-    pub fn new(window: @mut Window, elements: ~[AbstractNode]) -> @mut HTMLCollection {
-        reflect_dom_object(@mut HTMLCollection::new_inherited(window, elements),
-                           window, HTMLCollectionBinding::Wrap)
+    pub fn new(window: &JS<Window>, elements: ~[JS<Element>]) -> JS<HTMLCollection> {
+        reflect_dom_object(~HTMLCollection::new_inherited(window.clone(), elements),
+                           window.get(), HTMLCollectionBinding::Wrap)
     }
     
     pub fn Length(&self) -> u32 {
         self.elements.len() as u32
     }
 
-    pub fn Item(&self, index: u32) -> Option<AbstractNode> {
+    pub fn Item(&self, index: u32) -> Option<JS<Element>> {
         if index < self.Length() {
-            Some(self.elements[index])
+            Some(self.elements[index].clone())
         } else {
             None
         }
@@ -49,7 +51,7 @@ impl HTMLCollection {
         Ok(ptr::null())
     }
 
-    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<AbstractNode> {
+    pub fn IndexedGetter(&self, index: u32, found: &mut bool) -> Option<JS<Element>> {
         *found = true;
         self.Item(index)
     }

src/components/script/dom/htmldataelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDataElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLDataElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLDataElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLDataElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLDataElementDerived for EventTarget {
+    fn is_htmldataelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLDataElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDataElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLDataElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLDataElement {
         HTMLDataElement {
             htmlelement: HTMLElement::new_inherited(HTMLDataElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLDataElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLDataElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLDataElement> {
+        let element = HTMLDataElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLDataElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmldatalistelement.rs

@@ -3,33 +3,47 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDataListElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLDataListElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLDataListElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlcollection::HTMLCollection;
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLDataListElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLDataListElementDerived for EventTarget {
+    fn is_htmldatalistelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLDataListElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDataListElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLDataListElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLDataListElement {
         HTMLDataListElement {
             htmlelement: HTMLElement::new_inherited(HTMLDataListElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLDataListElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLDataListElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLDataListElement> {
+        let element = HTMLDataListElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLDataListElementBinding::Wrap)
     }
 }
 
 impl HTMLDataListElement {
-    pub fn Options(&self) -> @mut HTMLCollection {
-        let window = self.htmlelement.element.node.owner_doc().document().window;
-        HTMLCollection::new(window, ~[])
+    pub fn Options(&self) -> JS<HTMLCollection> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        HTMLCollection::new(&doc.window, ~[])
     }
 }

src/components/script/dom/htmldirectoryelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDirectoryElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLDirectoryElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLDirectoryElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLDirectoryElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLDirectoryElementDerived for EventTarget {
+    fn is_htmldirectoryelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLDirectoryElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDirectoryElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLDirectoryElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLDirectoryElement {
         HTMLDirectoryElement {
             htmlelement: HTMLElement::new_inherited(HTMLDirectoryElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLDirectoryElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLDirectoryElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLDirectoryElement> {
+        let element = HTMLDirectoryElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLDirectoryElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmldivelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDivElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLDivElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLDivElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLDivElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLDivElementDerived for EventTarget {
+    fn is_htmldivelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLDivElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDivElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLDivElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLDivElement {
         HTMLDivElement {
             htmlelement: HTMLElement::new_inherited(HTMLDivElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLDivElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLDivElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLDivElement> {
+        let element = HTMLDivElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLDivElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmldlistelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDListElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLDListElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLDListElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLDListElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLDListElementDerived for EventTarget {
+    fn is_htmldlistelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLDListElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDListElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLDListElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLDListElement {
         HTMLDListElement {
             htmlelement: HTMLElement::new_inherited(HTMLDListElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLDListElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLDListElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLDListElement> {
+        let element = HTMLDListElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLDListElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmldocument.rs

@@ -3,67 +3,80 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLDocumentBinding;
-use dom::bindings::utils::{Reflectable, Reflector, Traceable};
-use dom::document::{AbstractDocument, Document, HTML};
+use dom::bindings::codegen::InheritTypes::HTMLDocumentDerived;
+use dom::bindings::js::JS;
+use dom::bindings::utils::{Reflectable, Reflector};
+use dom::document::{Document, HTML, HTMLDocumentTypeId};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlcollection::HTMLCollection;
+use dom::node::DocumentNodeTypeId;
 use dom::window::Window;
 use servo_util::namespace::Null;
 
 use extra::url::Url;
-use js::jsapi::JSTracer;
 
+#[deriving(Encodable)]
 pub struct HTMLDocument {
     parent: Document
 }
 
+impl HTMLDocumentDerived for EventTarget {
+    fn is_htmldocument(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(DocumentNodeTypeId(HTMLDocumentTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLDocument {
-    pub fn new_inherited(window: @mut Window, url: Option<Url>) -> HTMLDocument {
+    pub fn new_inherited(window: JS<Window>, url: Option<Url>) -> HTMLDocument {
         HTMLDocument {
             parent: Document::new_inherited(window, url, HTML, None)
         }
     }
 
-    pub fn new(window: @mut Window, url: Option<Url>) -> AbstractDocument {
-        let document = HTMLDocument::new_inherited(window, url);
-        Document::reflect_document(@mut document, window, HTMLDocumentBinding::Wrap)
+    pub fn new(window: &JS<Window>, url: Option<Url>) -> JS<HTMLDocument> {
+        let document = HTMLDocument::new_inherited(window.clone(), url);
+        Document::reflect_document(~document, window, HTMLDocumentBinding::Wrap)
     }
 }
 
 impl HTMLDocument {
-    pub fn Images(&self) -> @mut HTMLCollection {
+    pub fn Images(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| "img" == elem.tag_name)
     }
 
-    pub fn Embeds(&self) -> @mut HTMLCollection {
+    pub fn Embeds(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| "embed" == elem.tag_name)
     }
 
-    pub fn Plugins(&self) -> @mut HTMLCollection {
+    pub fn Plugins(&self) -> JS<HTMLCollection> {
         self.Embeds()
     }
 
-    pub fn Links(&self) -> @mut HTMLCollection {
+    pub fn Links(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| {
             ("a" == elem.tag_name || "area" == elem.tag_name) &&
             elem.get_attribute(Null, "href").is_some()
         })
     }
 
-    pub fn Forms(&self) -> @mut HTMLCollection {
+    pub fn Forms(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| "form" == elem.tag_name)
     }
 
-    pub fn Scripts(&self) -> @mut HTMLCollection {
+    pub fn Scripts(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| "script" == elem.tag_name)
     }
 
-    pub fn Anchors(&self) -> @mut HTMLCollection {
+    pub fn Anchors(&self) -> JS<HTMLCollection> {
         self.parent.createHTMLCollection(|elem| {
             "a" == elem.tag_name && elem.get_attribute(Null, "name").is_some()
         })
     }
 
-    pub fn Applets(&self) -> @mut HTMLCollection {
+    pub fn Applets(&self) -> JS<HTMLCollection> {
         // FIXME: This should be return OBJECT elements containing applets.
         self.parent.createHTMLCollection(|elem| "applet" == elem.tag_name)
     }
@@ -78,9 +91,3 @@ impl Reflectable for HTMLDocument {
         self.parent.mut_reflector()
     }
 }
-
-impl Traceable for HTMLDocument {
-    fn trace(&self, tracer: *mut JSTracer) {
-        self.parent.trace(tracer);
-    }
-}

src/components/script/dom/htmlelement.rs

@@ -3,29 +3,42 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLElementBinding;
-use dom::bindings::utils::{Fallible, ErrorResult};
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLElementDerived;
+use dom::bindings::js::JS;
+use dom::bindings::utils::{ErrorResult, Fallible};
+use dom::document::Document;
 use dom::element::{Element, ElementTypeId, HTMLElementTypeId};
-use dom::node::{AbstractNode, Node};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::node::{Node, ElementNodeTypeId};
 use js::jsapi::{JSContext, JSVal};
 use js::JSVAL_NULL;
 use servo_util::namespace;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLElement {
     element: Element
 }
 
+impl HTMLElementDerived for EventTarget {
+    fn is_htmlelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(_)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLElement {
-    pub fn new_inherited(type_id: ElementTypeId, tag_name: DOMString, document: AbstractDocument) -> HTMLElement {
+    pub fn new_inherited(type_id: ElementTypeId, tag_name: DOMString, document: JS<Document>) -> HTMLElement {
         HTMLElement {
             element: Element::new_inherited(type_id, tag_name, namespace::HTML, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLElement::new_inherited(HTMLElementTypeId, localName, document);
-        Node::reflect_node(@mut element, document, HTMLElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLElement> {
+        let element = HTMLElement::new_inherited(HTMLElementTypeId, localName, document.clone());
+        Node::reflect_node(~element, document, HTMLElementBinding::Wrap)
     }
 }
 
@@ -134,7 +147,7 @@ impl HTMLElement {
     pub fn SetClassName(&self, _class: DOMString) {
     }
 
-    pub fn GetOffsetParent(&self) -> Option<AbstractNode> {
+    pub fn GetOffsetParent(&self) -> Option<JS<Element>> {
         None
     }
 

src/components/script/dom/htmlembedelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLEmbedElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLEmbedElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLEmbedElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLEmbedElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLEmbedElementDerived for EventTarget {
+    fn is_htmlembedelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLEmbedElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLEmbedElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLEmbedElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLEmbedElement {
         HTMLEmbedElement {
             htmlelement: HTMLElement::new_inherited(HTMLEmbedElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLEmbedElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLEmbedElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLEmbedElement> {
+        let element = HTMLEmbedElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLEmbedElementBinding::Wrap)
     }
 }
 
@@ -76,7 +89,7 @@ impl HTMLEmbedElement {
         Ok(())
     }
 
-    pub fn GetSVGDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetSVGDocument(&self) -> Option<JS<Document>> {
         None
     }
 }

src/components/script/dom/htmlfieldsetelement.rs

@@ -3,29 +3,43 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLFieldSetElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLFieldSetElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLFieldSetElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::htmlformelement::HTMLFormElement;
 use dom::htmlcollection::HTMLCollection;
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use dom::validitystate::ValidityState;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLFieldSetElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLFieldSetElementDerived for EventTarget {
+    fn is_htmlfieldsetelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLFieldSetElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLFieldSetElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLFieldSetElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFieldSetElement {
         HTMLFieldSetElement {
             htmlelement: HTMLElement::new_inherited(HTMLFieldSetElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLFieldSetElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLFieldSetElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFieldSetElement> {
+        let element = HTMLFieldSetElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLFieldSetElementBinding::Wrap)
     }
 }
 
@@ -38,7 +52,7 @@ impl HTMLFieldSetElement {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 
@@ -54,18 +68,20 @@ impl HTMLFieldSetElement {
         ~""
     }
 
-    pub fn Elements(&self) -> @mut HTMLCollection {
-        let window = self.htmlelement.element.node.owner_doc().document().window;
-        HTMLCollection::new(window, ~[])
+    pub fn Elements(&self) -> JS<HTMLCollection> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        HTMLCollection::new(&doc.window, ~[])
     }
 
     pub fn WillValidate(&self) -> bool {
         false
     }
 
-    pub fn Validity(&self) -> @mut ValidityState {
-        let global = self.htmlelement.element.node.owner_doc().document().window;
-        ValidityState::new(global)
+    pub fn Validity(&self) -> JS<ValidityState> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        ValidityState::new(&doc.window)
     }
 
     pub fn ValidationMessage(&self) -> DOMString {

src/components/script/dom/htmlfontelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLFontElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLFontElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLFontElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLFontElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLFontElementDerived for EventTarget {
+    fn is_htmlfontelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLFontElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLFontElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLFontElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFontElement {
         HTMLFontElement {
             htmlelement: HTMLElement::new_inherited(HTMLFontElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLFontElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLFontElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFontElement> {
+        let element = HTMLFontElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLFontElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlformelement.rs

@@ -3,28 +3,41 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLFormElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLFormElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
-use dom::element::HTMLFormElementTypeId;
+use dom::document::Document;
+use dom::element::{Element, HTMLFormElementTypeId};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlcollection::HTMLCollection;
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLFormElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLFormElementDerived for EventTarget {
+    fn is_htmlformelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLFormElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLFormElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLFormElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFormElement {
         HTMLFormElement {
             htmlelement: HTMLElement::new_inherited(HTMLFormElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLFormElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLFormElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFormElement> {
+        let element = HTMLFormElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLFormElementBinding::Wrap)
     }
 }
 
@@ -101,9 +114,10 @@ impl HTMLFormElement {
         Ok(())
     }
 
-    pub fn Elements(&self) -> @mut HTMLCollection {
-        let window = self.htmlelement.element.node.owner_doc().document().window;
-        HTMLCollection::new(window, ~[])
+    pub fn Elements(&self) -> JS<HTMLCollection> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        HTMLCollection::new(&doc.window, ~[])
     }
 
     pub fn Length(&self) -> i32 {
@@ -121,7 +135,7 @@ impl HTMLFormElement {
         false
     }
 
-    pub fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> AbstractNode {
+    pub fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> JS<Element> {
         fail!("Not implemented.")
     }
 }

src/components/script/dom/htmlframeelement.rs

@@ -3,28 +3,41 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLFrameElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLFrameElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLFrameElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use dom::windowproxy::WindowProxy;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLFrameElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLFrameElementDerived for EventTarget {
+    fn is_htmlframeelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLFrameElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLFrameElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLFrameElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFrameElement {
         HTMLFrameElement {
             htmlelement: HTMLElement::new_inherited(HTMLFrameElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLFrameElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLFrameElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFrameElement> {
+        let element = HTMLFrameElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLFrameElementBinding::Wrap)
     }
 }
 
@@ -77,11 +90,11 @@ impl HTMLFrameElement {
         Ok(())
     }
 
-    pub fn GetContentDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetContentDocument(&self) -> Option<JS<Document>> {
         None
     }
 
-    pub fn GetContentWindow(&self) -> Option<@mut WindowProxy> {
+    pub fn GetContentWindow(&self) -> Option<JS<WindowProxy>> {
         None
     }
 

src/components/script/dom/htmlframesetelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLFrameSetElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLFrameSetElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLFrameSetElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLFrameSetElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLFrameSetElementDerived for EventTarget {
+    fn is_htmlframesetelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLFrameSetElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLFrameSetElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLFrameSetElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFrameSetElement {
         HTMLFrameSetElement {
             htmlelement: HTMLElement::new_inherited(HTMLFrameSetElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLFrameSetElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLFrameSetElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFrameSetElement> {
+        let element = HTMLFrameSetElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLFrameSetElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlheadelement.rs

@@ -3,25 +3,38 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLHeadElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLHeadElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLHeadElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLHeadElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLHeadElementDerived for EventTarget {
+    fn is_htmlheadelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLHeadElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLHeadElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLHeadElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLHeadElement {
         HTMLHeadElement {
             htmlelement: HTMLElement::new_inherited(HTMLHeadElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLHeadElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLHeadElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLHeadElement> {
+        let element = HTMLHeadElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLHeadElementBinding::Wrap)
     }
 }

src/components/script/dom/htmlheadingelement.rs

@@ -3,12 +3,16 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLHeadingElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLHeadingElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLHeadingElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub enum HeadingLevel {
     Heading1,
     Heading2,
@@ -18,22 +22,32 @@ pub enum HeadingLevel {
     Heading6,
 }
 
+#[deriving(Encodable)]
 pub struct HTMLHeadingElement {
     htmlelement: HTMLElement,
     level: HeadingLevel,
 }
 
+impl HTMLHeadingElementDerived for EventTarget {
+    fn is_htmlheadingelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLHeadingElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLHeadingElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument, level: HeadingLevel) -> HTMLHeadingElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>, level: HeadingLevel) -> HTMLHeadingElement {
         HTMLHeadingElement {
             htmlelement: HTMLElement::new_inherited(HTMLHeadingElementTypeId, localName, document),
             level: level,
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument, level: HeadingLevel) -> AbstractNode {
-        let element = HTMLHeadingElement::new_inherited(localName, document, level);
-        Node::reflect_node(@mut element, document, HTMLHeadingElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>, level: HeadingLevel) -> JS<HTMLHeadingElement> {
+        let element = HTMLHeadingElement::new_inherited(localName, document.clone(), level);
+        Node::reflect_node(~element, document, HTMLHeadingElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlhrelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLHRElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLHRElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLHRElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLHRElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLHRElementDerived for EventTarget {
+    fn is_htmlhrelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLHRElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLHRElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLHRElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLHRElement {
         HTMLHRElement {
             htmlelement: HTMLElement::new_inherited(HTMLHRElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLHRElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLHRElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLHRElement> {
+        let element = HTMLHRElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLHRElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlhtmlelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLHtmlElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLHtmlElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLHtmlElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLHtmlElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLHtmlElementDerived for EventTarget {
+    fn is_htmlhtmlelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLHtmlElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLHtmlElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLHtmlElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLHtmlElement {
         HTMLHtmlElement {
             htmlelement: HTMLElement::new_inherited(HTMLHtmlElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLHtmlElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLHtmlElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLHtmlElement> {
+        let element = HTMLHtmlElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLHtmlElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmliframeelement.rs

@@ -3,17 +3,21 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLIFrameElementBinding;
+use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLIFrameElementDerived};
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLIframeElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use dom::windowproxy::WindowProxy;
 use servo_util::str::DOMString;
 
 use extra::url::Url;
 use servo_msg::constellation_msg::{PipelineId, SubpageId};
 use std::ascii::StrAsciiExt;
+use extra::serialize::{Encoder, Encodable};
 
 enum SandboxAllowance {
     AllowNothing = 0x00,
@@ -25,13 +29,33 @@ enum SandboxAllowance {
     AllowPopups = 0x20
 }
 
+#[deriving(Encodable)]
 pub struct HTMLIFrameElement {
     htmlelement: HTMLElement,
-    frame: Option<Url>,
+    extra: Untraceable,
     size: Option<IFrameSize>,
     sandbox: Option<u8>
 }
 
+struct Untraceable {
+    frame: Option<Url>,
+}
+
+impl<S: Encoder> Encodable<S> for Untraceable {
+    fn encode(&self, _s: &mut S) {
+    }
+}
+
+impl HTMLIFrameElementDerived for EventTarget {
+    fn is_htmliframeelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLIframeElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
+#[deriving(Encodable)]
 pub struct IFrameSize {
     pipeline_id: PipelineId,
     subpage_id: SubpageId,
@@ -44,18 +68,20 @@ impl HTMLIFrameElement {
 }
 
 impl HTMLIFrameElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLIFrameElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLIFrameElement {
         HTMLIFrameElement {
             htmlelement: HTMLElement::new_inherited(HTMLIframeElementTypeId, localName, document),
-            frame: None,
+            extra: Untraceable {
+                frame: None
+            },
             size: None,
             sandbox: None,
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLIFrameElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLIFrameElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLIFrameElement> {
+        let element = HTMLIFrameElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLIFrameElementBinding::Wrap)
     }
 }
 
@@ -84,12 +110,13 @@ impl HTMLIFrameElement {
         Ok(())
     }
 
-    pub fn Sandbox(&self, _abstract_self: AbstractNode) -> DOMString {
+    pub fn Sandbox(&self, _abstract_self: &JS<HTMLIFrameElement>) -> DOMString {
         self.htmlelement.element.get_string_attribute("sandbox")
     }
 
-    pub fn SetSandbox(&mut self, abstract_self: AbstractNode, sandbox: DOMString) {
-        self.htmlelement.element.set_string_attribute(abstract_self, "sandbox",
+    pub fn SetSandbox(&mut self, abstract_self: &JS<HTMLIFrameElement>, sandbox: DOMString) {
+        self.htmlelement.element.set_string_attribute(&ElementCast::from(abstract_self),
+                                                      "sandbox",
                                                       sandbox);
     }
 
@@ -143,11 +170,11 @@ impl HTMLIFrameElement {
         Ok(())
     }
 
-    pub fn GetContentDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetContentDocument(&self) -> Option<JS<Document>> {
         None
     }
 
-    pub fn GetContentWindow(&self) -> Option<@mut WindowProxy> {
+    pub fn GetContentWindow(&self) -> Option<JS<WindowProxy>> {
         None
     }
 
@@ -199,7 +226,7 @@ impl HTMLIFrameElement {
         Ok(())
     }
 
-    pub fn GetSVGDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetSVGDocument(&self) -> Option<JS<Document>> {
         None
     }
 }

src/components/script/dom/htmlimageelement.rs

@@ -3,11 +3,15 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLImageElementBinding;
+use dom::bindings::codegen::InheritTypes::{NodeCast, HTMLImageElementDerived};
+use dom::bindings::codegen::InheritTypes::{ElementCast};
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
-use dom::element::HTMLImageElementTypeId;
+use dom::document::Document;
+use dom::element::{Element, HTMLImageElementTypeId};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId, NodeHelpers};
 use extra::url::Url;
 use servo_util::geometry::to_px;
 use layout_interface::{ContentBoxQuery, ContentBoxResponse};
@@ -17,22 +21,45 @@ use servo_util::url::parse_url;
 use servo_util::namespace::Null;
 use servo_util::str::DOMString;
 
+use extra::serialize::{Encoder, Encodable};
+
+#[deriving(Encodable)]
 pub struct HTMLImageElement {
     htmlelement: HTMLElement,
+    extra: Untraceable,
+}
+
+struct Untraceable {
     image: Option<Url>,
 }
 
+impl<S: Encoder> Encodable<S> for Untraceable {
+    fn encode(&self, _s: &mut S) {
+    }
+}
+
+impl HTMLImageElementDerived for EventTarget {
+    fn is_htmlimageelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLImageElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLImageElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLImageElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLImageElement {
         HTMLImageElement {
             htmlelement: HTMLElement::new_inherited(HTMLImageElementTypeId, localName, document),
+            extra: Untraceable {
                 image: None,
             }
         }
+    }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLImageElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLImageElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLImageElement> {
+        let element = HTMLImageElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLImageElementBinding::Wrap)
     }
 }
 
@@ -41,12 +68,12 @@ impl HTMLImageElement {
     /// prefetching the image. This method must be called after `src` is changed.
     pub fn update_image(&mut self, image_cache: ImageCacheTask, url: Option<Url>) {
         let elem = &mut self.htmlelement.element;
-        let src_opt = elem.get_attribute(Null, "src").map(|x| x.Value());
+        let src_opt = elem.get_attribute(Null, "src").map(|x| x.get().Value());
         match src_opt {
             None => {}
             Some(src) => {
                 let img_url = parse_url(src, url);
-                self.image = Some(img_url.clone());
+                self.extra.image = Some(img_url.clone());
 
                 // inform the image cache to load this, but don't store a
                 // handle.
@@ -61,7 +88,7 @@ impl HTMLImageElement {
     pub fn AfterSetAttr(&mut self, name: DOMString, _value: DOMString) {
         if "src" == name {
             let document = self.htmlelement.element.node.owner_doc();
-            let window = document.document().window;
+            let window = document.get().window.get();
             let url = window.page.url.as_ref().map(|&(ref url, _)| url.clone());
             self.update_image(window.image_cache_task.clone(), url);
         }
@@ -73,7 +100,7 @@ impl HTMLImageElement {
         // `self.update_image()` will see the missing src attribute and return early.
         if "src" == name {
             let document = self.htmlelement.element.node.owner_doc();
-            let window = document.document().window;
+            let window = document.get().window.get();
             self.update_image(window.image_cache_task.clone(), None);
         }
     }
@@ -86,13 +113,13 @@ impl HTMLImageElement {
         Ok(())
     }
 
-    pub fn Src(&self, _abstract_self: AbstractNode) -> DOMString {
+    pub fn Src(&self, _abstract_self: &JS<HTMLImageElement>) -> DOMString {
         ~""
     }
 
-    pub fn SetSrc(&mut self, abstract_self: AbstractNode, src: DOMString) -> ErrorResult {
+    pub fn SetSrc(&mut self, abstract_self: &JS<HTMLImageElement>, src: DOMString) -> ErrorResult {
         let node = &mut self.htmlelement.element;
-        node.set_attr(abstract_self, ~"src", src.clone());
+        node.set_attr(&ElementCast::from(abstract_self), ~"src", src.clone());
         Ok(())
     }
 
@@ -120,37 +147,43 @@ impl HTMLImageElement {
         Ok(())
     }
 
-    pub fn Width(&self, abstract_self: AbstractNode) -> u32 {
-        let node = &self.htmlelement.element.node;
-        let page = node.owner_doc().document().window.page;
+    pub fn Width(&self, abstract_self: &JS<HTMLImageElement>) -> u32 {
+        let node: JS<Node> = NodeCast::from(abstract_self);
+        let doc = node.get().owner_doc();
+        let page = doc.get().window.get().page;
         let (port, chan) = Chan::new();
-        match page.query_layout(ContentBoxQuery(abstract_self, chan), port) {
+        let addr = node.to_trusted_node_address();
+        match page.query_layout(ContentBoxQuery(addr, chan), port) {
             ContentBoxResponse(rect) => {
                 to_px(rect.size.width) as u32
             }
         }
     }
 
-    pub fn SetWidth(&mut self, abstract_self: AbstractNode, width: u32) -> ErrorResult {
-        let node = &mut self.htmlelement.element;
-        node.set_attr(abstract_self, ~"width", width.to_str());
+    pub fn SetWidth(&mut self, abstract_self: &JS<HTMLImageElement>, width: u32) -> ErrorResult {
+        let mut elem: JS<Element> = ElementCast::from(abstract_self);
+        let mut elem_clone = elem.clone();
+        elem.get_mut().set_attr(&mut elem_clone, ~"width", width.to_str());
         Ok(())
     }
 
-    pub fn Height(&self, abstract_self: AbstractNode) -> u32 {
+    pub fn Height(&self, abstract_self: &JS<HTMLImageElement>) -> u32 {
         let node = &self.htmlelement.element.node;
-        let page = node.owner_doc().document().window.page;
+        let doc = node.owner_doc();
+        let page = doc.get().window.get().page;
         let (port, chan) = Chan::new();
-        match page.query_layout(ContentBoxQuery(abstract_self, chan), port) {
+        let this_node: JS<Node> = NodeCast::from(abstract_self);
+        let addr = this_node.to_trusted_node_address();
+        match page.query_layout(ContentBoxQuery(addr, chan), port) {
             ContentBoxResponse(rect) => {
                 to_px(rect.size.height) as u32
             }
         }
     }
 
-    pub fn SetHeight(&mut self, abstract_self: AbstractNode, height: u32) -> ErrorResult {
+    pub fn SetHeight(&mut self, abstract_self: &JS<HTMLImageElement>, height: u32) -> ErrorResult {
         let node = &mut self.htmlelement.element;
-        node.set_attr(abstract_self, ~"height", height.to_str());
+        node.set_attr(&ElementCast::from(abstract_self), ~"height", height.to_str());
         Ok(())
     }
 

src/components/script/dom/htmlinputelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLInputElementBinding;
-use dom::bindings::utils::{Fallible, ErrorResult};
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLInputElementDerived;
+use dom::bindings::js::JS;
+use dom::bindings::utils::{ErrorResult, Fallible};
+use dom::document::Document;
 use dom::element::HTMLInputElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLInputElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLInputElementDerived for EventTarget {
+    fn is_htmlinputelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLInputElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLInputElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLInputElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLInputElement {
         HTMLInputElement {
             htmlelement: HTMLElement::new_inherited(HTMLInputElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLInputElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLInputElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLInputElement> {
+        let element = HTMLInputElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLInputElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmllabelelement.rs

@@ -3,26 +3,39 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLLabelElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLLabelElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLLabelElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLLabelElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLLabelElementDerived for EventTarget {
+    fn is_htmllabelelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLLabelElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLLabelElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLLabelElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLLabelElement {
         HTMLLabelElement {
             htmlelement: HTMLElement::new_inherited(HTMLLabelElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLLabelElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLLabelElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLLabelElement> {
+        let element = HTMLLabelElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLLabelElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmllegendelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLLegendElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLLegendElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLLegendElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLLegendElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLLegendElementDerived for EventTarget {
+    fn is_htmllegendelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLLegendElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLLegendElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLLegendElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLLegendElement {
         HTMLLegendElement {
             htmlelement: HTMLElement::new_inherited(HTMLLegendElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLLegendElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLLegendElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLLegendElement> {
+        let element = HTMLLegendElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLLegendElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmllielement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLLIElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLLIElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLLIElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLLIElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLLIElementDerived for EventTarget {
+    fn is_htmllielement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLLIElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLLIElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLLIElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLLIElement {
         HTMLLIElement {
             htmlelement: HTMLElement::new_inherited(HTMLLIElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLLIElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLLIElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLLIElement> {
+        let element = HTMLLIElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLLIElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmllinkelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLLinkElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLLinkElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLLinkElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLLinkElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLLinkElementDerived for EventTarget {
+    fn is_htmllinkelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLLinkElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLLinkElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLLinkElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLLinkElement {
         HTMLLinkElement {
             htmlelement: HTMLElement::new_inherited(HTMLLinkElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLLinkElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLLinkElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLLinkElement> {
+        let element = HTMLLinkElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLLinkElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlmainelement.rs

@@ -3,25 +3,38 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLMainElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLMainElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLMainElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLMainElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLMainElementDerived for EventTarget {
+    fn is_htmlmainelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLMainElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLMainElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLMainElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLMainElement {
         HTMLMainElement {
             htmlelement: HTMLElement::new_inherited(HTMLMainElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLMainElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLMainElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLMainElement> {
+        let element = HTMLMainElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLMainElementBinding::Wrap)
     }
 }

src/components/script/dom/htmlmapelement.rs

@@ -3,28 +3,41 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLMapElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLMapElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::htmlcollection::HTMLCollection;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLMapElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::htmlcollection::HTMLCollection;
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLMapElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLMapElementDerived for EventTarget {
+    fn is_htmlmapelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLMapElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLMapElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLMapElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLMapElement {
         HTMLMapElement {
             htmlelement: HTMLElement::new_inherited(HTMLMapElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLMapElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLMapElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLMapElement> {
+        let element = HTMLMapElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLMapElementBinding::Wrap)
     }
 }
 
@@ -37,8 +50,9 @@ impl HTMLMapElement {
         Ok(())
     }
 
-    pub fn Areas(&self) -> @mut HTMLCollection {
-        let window = self.htmlelement.element.node.owner_doc().document().window;
-        HTMLCollection::new(window, ~[])
+    pub fn Areas(&self) -> JS<HTMLCollection> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        HTMLCollection::new(&doc.window, ~[])
     }
 }

src/components/script/dom/htmlmediaelement.rs

@@ -2,18 +2,33 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::bindings::js::JS;
+use dom::bindings::codegen::InheritTypes::HTMLMediaElementDerived;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
-use dom::element::ElementTypeId;
+use dom::document::Document;
+use dom::element::{ElementTypeId, HTMLAudioElementTypeId, HTMLVideoElementTypeId};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
+use dom::node::ElementNodeTypeId;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLMediaElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLMediaElementDerived for EventTarget {
+    fn is_htmlmediaelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLVideoElementTypeId)) |
+            NodeTargetTypeId(ElementNodeTypeId(HTMLAudioElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLMediaElement {
-    pub fn new_inherited(type_id: ElementTypeId, tag_name: DOMString, document: AbstractDocument) -> HTMLMediaElement {
+    pub fn new_inherited(type_id: ElementTypeId, tag_name: DOMString, document: JS<Document>) -> HTMLMediaElement {
         HTMLMediaElement {
             htmlelement: HTMLElement::new_inherited(type_id, tag_name, document)
         }

src/components/script/dom/htmlmetaelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLMetaElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLMetaElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLMetaElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLMetaElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLMetaElementDerived for EventTarget {
+    fn is_htmlmetaelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLMetaElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLMetaElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLMetaElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLMetaElement {
         HTMLMetaElement {
             htmlelement: HTMLElement::new_inherited(HTMLMetaElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLMetaElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLMetaElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLMetaElement> {
+        let element = HTMLMetaElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLMetaElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlmeterelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLMeterElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLMeterElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLMeterElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLMeterElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLMeterElementDerived for EventTarget {
+    fn is_htmlmeterelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLMeterElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLMeterElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLMeterElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLMeterElement {
         HTMLMeterElement {
             htmlelement: HTMLElement::new_inherited(HTMLMeterElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLMeterElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLMeterElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLMeterElement> {
+        let element = HTMLMeterElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLMeterElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlmodelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLModElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLModElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLModElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLModElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLModElementDerived for EventTarget {
+    fn is_htmlmodelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLModElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLModElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLModElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLModElement {
         HTMLModElement {
             htmlelement: HTMLElement::new_inherited(HTMLModElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLModElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLModElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLModElement> {
+        let element = HTMLModElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLModElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlobjectelement.rs

@@ -3,11 +3,15 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLObjectElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLObjectElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLObjectElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::htmlformelement::HTMLFormElement;
+use dom::node::{Node, ElementNodeTypeId};
 use dom::validitystate::ValidityState;
 use dom::windowproxy::WindowProxy;
 use servo_util::str::DOMString;
@@ -19,20 +23,30 @@ use servo_util::url::parse_url;
 use servo_util::namespace::Null;
 use servo_util::url::is_image_data;
 
+#[deriving(Encodable)]
 pub struct HTMLObjectElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLObjectElementDerived for EventTarget {
+    fn is_htmlobjectelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLObjectElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLObjectElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLObjectElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLObjectElement {
         HTMLObjectElement {
             htmlelement: HTMLElement::new_inherited(HTMLObjectElementTypeId, localName, document),
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLObjectElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLObjectElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLObjectElement> {
+        let element = HTMLObjectElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLObjectElementBinding::Wrap)
     }
 }
 
@@ -44,8 +58,8 @@ impl HTMLObjectElement {
         let elem = &mut self.htmlelement.element;
 
         // TODO: support other values
-        match (elem.get_attribute(Null, "type").map(|x| x.Value()),
-               elem.get_attribute(Null, "data").map(|x| x.Value())) {
+        match (elem.get_attribute(Null, "type").map(|x| x.get().Value()),
+               elem.get_attribute(Null, "data").map(|x| x.get().Value())) {
             (None, Some(uri)) => {
                 if is_image_data(uri) {
                     let data_url = parse_url(uri, url);
@@ -60,9 +74,9 @@ impl HTMLObjectElement {
     pub fn AfterSetAttr(&mut self, name: DOMString, _value: DOMString) {
         if "data" == name {
             let document = self.htmlelement.element.node.owner_doc();
-            let window = document.document().window;
-            let url = window.page.url.as_ref().map(|&(ref url, _)| url.clone());
-            self.process_data_url(window.image_cache_task.clone(), url);
+            let window = document.get().window.clone();
+            let url = window.get().page.url.as_ref().map(|&(ref url, _)| url.clone());
+            self.process_data_url(window.get().image_cache_task.clone(), url);
         }
     }
 
@@ -98,7 +112,7 @@ impl HTMLObjectElement {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 
@@ -118,11 +132,11 @@ impl HTMLObjectElement {
         Ok(())
     }
 
-    pub fn GetContentDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetContentDocument(&self) -> Option<JS<Document>> {
         None
     }
 
-    pub fn GetContentWindow(&self) -> Option<@mut WindowProxy> {
+    pub fn GetContentWindow(&self) -> Option<JS<WindowProxy>> {
         None
     }
 
@@ -130,9 +144,10 @@ impl HTMLObjectElement {
         false
     }
 
-    pub fn Validity(&self) -> @mut ValidityState {
-        let global = self.htmlelement.element.node.owner_doc().document().window;
-        ValidityState::new(global)
+    pub fn Validity(&self) -> JS<ValidityState> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        ValidityState::new(&doc.window)
     }
 
     pub fn ValidationMessage(&self) -> DOMString {
@@ -226,7 +241,7 @@ impl HTMLObjectElement {
         Ok(())
     }
 
-    pub fn GetSVGDocument(&self) -> Option<AbstractDocument> {
+    pub fn GetSVGDocument(&self) -> Option<JS<Document>> {
         None
     }
 }

src/components/script/dom/htmlolistelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLOListElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLOListElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLOListElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLOListElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLOListElementDerived for EventTarget {
+    fn is_htmlolistelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLOListElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLOListElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLOListElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLOListElement {
         HTMLOListElement {
             htmlelement: HTMLElement::new_inherited(HTMLOListElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLOListElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLOListElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLOListElement> {
+        let element = HTMLOListElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLOListElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmloptgroupelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLOptGroupElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLOptGroupElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLOptGroupElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLOptGroupElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLOptGroupElementDerived for EventTarget {
+    fn is_htmloptgroupelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLOptGroupElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLOptGroupElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLOptGroupElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLOptGroupElement {
         HTMLOptGroupElement {
             htmlelement: HTMLElement::new_inherited(HTMLOptGroupElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLOptGroupElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLOptGroupElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLOptGroupElement> {
+        let element = HTMLOptGroupElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLOptGroupElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmloptionelement.rs

@@ -3,27 +3,41 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLOptionElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLOptionElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLOptionElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::htmlformelement::HTMLFormElement;
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLOptionElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLOptionElementDerived for EventTarget {
+    fn is_htmloptionelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLOptionElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLOptionElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLOptionElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLOptionElement {
         HTMLOptionElement {
             htmlelement: HTMLElement::new_inherited(HTMLOptionElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLOptionElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLOptionElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLOptionElement> {
+        let element = HTMLOptionElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLOptionElementBinding::Wrap)
     }
 }
 
@@ -36,7 +50,7 @@ impl HTMLOptionElement {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 

src/components/script/dom/htmloutputelement.rs

@@ -3,33 +3,47 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLOutputElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLOutputElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLOutputElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::htmlformelement::HTMLFormElement;
+use dom::node::{Node, ElementNodeTypeId};
 use dom::validitystate::ValidityState;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLOutputElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLOutputElementDerived for EventTarget {
+    fn is_htmloutputelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLOutputElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLOutputElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLOutputElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLOutputElement {
         HTMLOutputElement {
             htmlelement: HTMLElement::new_inherited(HTMLOutputElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLOutputElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLOutputElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLOutputElement> {
+        let element = HTMLOutputElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLOutputElementBinding::Wrap)
     }
 }
 
 impl HTMLOutputElement {
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 
@@ -68,12 +82,13 @@ impl HTMLOutputElement {
     pub fn SetWillValidate(&mut self, _will_validate: bool) {
     }
 
-    pub fn Validity(&self) -> @mut ValidityState {
-        let global = self.htmlelement.element.node.owner_doc().document().window;
-        ValidityState::new(global)
+    pub fn Validity(&self) -> JS<ValidityState> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        ValidityState::new(&doc.window)
     }
 
-    pub fn SetValidity(&mut self, _validity: @mut ValidityState) {
+    pub fn SetValidity(&mut self, _validity: JS<ValidityState>) {
     }
 
     pub fn ValidationMessage(&self) -> DOMString {

src/components/script/dom/htmlparagraphelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLParagraphElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLParagraphElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLParagraphElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLParagraphElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLParagraphElementDerived for EventTarget {
+    fn is_htmlparagraphelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLParagraphElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLParagraphElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLParagraphElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLParagraphElement {
         HTMLParagraphElement {
             htmlelement: HTMLElement::new_inherited(HTMLParagraphElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLParagraphElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLParagraphElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLParagraphElement> {
+        let element = HTMLParagraphElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLParagraphElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlparamelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLParamElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLParamElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLParamElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLParamElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLParamElementDerived for EventTarget {
+    fn is_htmlparamelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLParamElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLParamElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLParamElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLParamElement {
         HTMLParamElement {
             htmlelement: HTMLElement::new_inherited(HTMLParamElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLParamElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLParamElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLParamElement> {
+        let element = HTMLParamElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLParamElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlpreelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLPreElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLPreElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{ErrorResult};
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLPreElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLPreElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLPreElementDerived for EventTarget {
+    fn is_htmlpreelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLPreElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLPreElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLPreElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLPreElement {
         HTMLPreElement {
             htmlelement: HTMLElement::new_inherited(HTMLPreElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLPreElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLPreElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLPreElement> {
+        let element = HTMLPreElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLPreElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlprogresselement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLProgressElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLProgressElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::{ErrorResult, Fallible};
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLProgressElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLProgressElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLProgressElementDerived for EventTarget {
+    fn is_htmlprogresselement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLProgressElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLProgressElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLProgressElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLProgressElement {
         HTMLProgressElement {
             htmlelement: HTMLElement::new_inherited(HTMLProgressElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLProgressElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLProgressElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLProgressElement> {
+        let element = HTMLProgressElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLProgressElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlquoteelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLQuoteElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLQuoteElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLQuoteElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLQuoteElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLQuoteElementDerived for EventTarget {
+    fn is_htmlquoteelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLQuoteElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLQuoteElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLQuoteElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLQuoteElement {
         HTMLQuoteElement {
             htmlelement: HTMLElement::new_inherited(HTMLQuoteElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLQuoteElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLQuoteElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLQuoteElement> {
+        let element = HTMLQuoteElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLQuoteElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlscriptelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLScriptElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLScriptElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLScriptElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLScriptElement {
     htmlelement: HTMLElement,
 }
 
+impl HTMLScriptElementDerived for EventTarget {
+    fn is_htmlscriptelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLScriptElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLScriptElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLScriptElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLScriptElement {
         HTMLScriptElement {
             htmlelement: HTMLElement::new_inherited(HTMLScriptElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLScriptElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLScriptElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLScriptElement> {
+        let element = HTMLScriptElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLScriptElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlselectelement.rs

@@ -3,28 +3,43 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLSelectElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLSelectElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
-use dom::element::HTMLSelectElementTypeId;
+use dom::document::Document;
+use dom::element::{Element, HTMLSelectElementTypeId};
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::htmlformelement::HTMLFormElement;
+use dom::node::{Node, ElementNodeTypeId};
+use dom::htmloptionelement::HTMLOptionElement;
 use dom::validitystate::ValidityState;
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLSelectElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLSelectElementDerived for EventTarget {
+    fn is_htmlselectelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLSelectElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLSelectElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLSelectElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLSelectElement {
         HTMLSelectElement {
             htmlelement: HTMLElement::new_inherited(HTMLSelectElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLSelectElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLSelectElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLSelectElement> {
+        let element = HTMLSelectElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLSelectElementBinding::Wrap)
     }
 }
 
@@ -45,7 +60,7 @@ impl HTMLSelectElement {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<AbstractNode> {
+    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
         None
     }
 
@@ -93,19 +108,19 @@ impl HTMLSelectElement {
         Ok(())
     }
 
-    pub fn Item(&self, _index: u32) -> Option<AbstractNode> {
+    pub fn Item(&self, _index: u32) -> Option<JS<Element>> {
         None
     }
 
-    pub fn NamedItem(&self, _name: DOMString) -> Option<AbstractNode> {
+    pub fn NamedItem(&self, _name: DOMString) -> Option<JS<HTMLOptionElement>> {
         None
     }
 
-    pub fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> Option<AbstractNode> {
+    pub fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> Option<JS<Element>> {
         None
     }
 
-    pub fn IndexedSetter(&mut self, _index: u32, _option: Option<AbstractNode>) -> ErrorResult {
+    pub fn IndexedSetter(&mut self, _index: u32, _option: Option<JS<HTMLOptionElement>>) -> ErrorResult {
         Ok(())
     }
 
@@ -137,12 +152,13 @@ impl HTMLSelectElement {
     pub fn SetWillValidate(&mut self, _will_validate: bool) {
     }
 
-    pub fn Validity(&self) -> @mut ValidityState {
-        let global = self.htmlelement.element.node.owner_doc().document().window;
-        ValidityState::new(global)
+    pub fn Validity(&self) -> JS<ValidityState> {
+        let doc = self.htmlelement.element.node.owner_doc();
+        let doc = doc.get();
+        ValidityState::new(&doc.window)
     }
 
-    pub fn SetValidity(&mut self, _validity: @mut ValidityState) {
+    pub fn SetValidity(&mut self, _validity: JS<ValidityState>) {
     }
 
     pub fn ValidationMessage(&self) -> DOMString {

src/components/script/dom/htmlserializer.rs

@@ -4,10 +4,20 @@
 
 use servo_util::namespace;
 use dom::attr::Attr;
+use dom::bindings::codegen::InheritTypes::{ElementCast, TextCast, CommentCast};
+use dom::bindings::codegen::InheritTypes::{DocumentTypeCast, CharacterDataCast};
+use dom::bindings::codegen::InheritTypes::ProcessingInstructionCast;
+use dom::bindings::js::JS;
+use dom::characterdata::CharacterData;
+use dom::comment::Comment;
+use dom::documenttype::DocumentType;
+use dom::element::Element;
 use dom::node::NodeIterator;
 use dom::node::{DoctypeNodeTypeId, DocumentFragmentNodeTypeId, CommentNodeTypeId};
 use dom::node::{DocumentNodeTypeId, ElementNodeTypeId, ProcessingInstructionNodeTypeId};
-use dom::node::{TextNodeTypeId, AbstractNode};
+use dom::node::{TextNodeTypeId, NodeHelpers};
+use dom::processinginstruction::ProcessingInstruction;
+use dom::text::Text;
 
 pub fn serialize(iterator: &mut NodeIterator) -> ~str {
     let mut html = ~"";
@@ -20,19 +30,24 @@ pub fn serialize(iterator: &mut NodeIterator) -> ~str {
         html.push_str(
             match node.type_id() {
                 ElementNodeTypeId(..) => {
-                    serialize_elem(node, &mut open_elements)
+                    let elem: JS<Element> = ElementCast::to(&node);
+                    serialize_elem(&elem, &mut open_elements)
                 }
                 CommentNodeTypeId => {
-                    serialize_comment(node)
+                    let comment: JS<Comment> = CommentCast::to(&node);
+                    serialize_comment(&comment)
                 }
                 TextNodeTypeId => {
-                    serialize_text(node)
+                    let text: JS<Text> = TextCast::to(&node);
+                    serialize_text(&text)
                 }
                 DoctypeNodeTypeId => {
-                    serialize_doctype(node)
+                    let doctype: JS<DocumentType> = DocumentTypeCast::to(&node);
+                    serialize_doctype(&doctype)
                 }
                 ProcessingInstructionNodeTypeId => {
-                    serialize_processing_instruction(node)
+                    let processing_instruction: JS<ProcessingInstruction> = ProcessingInstructionCast::to(&node);
+                    serialize_processing_instruction(&processing_instruction)
                 }
                 DocumentFragmentNodeTypeId => {
                     ~""
@@ -49,88 +64,75 @@ pub fn serialize(iterator: &mut NodeIterator) -> ~str {
     html
 }
 
-fn serialize_comment(node: AbstractNode) -> ~str {
-    node.with_imm_characterdata(|comment| {
-        ~"<!--" + comment.data + "-->"
-    })
+fn serialize_comment(comment: &JS<Comment>) -> ~str {
+    ~"<!--" + comment.get().characterdata.data + "-->"
 }
 
-fn serialize_text(node: AbstractNode) -> ~str {
-    node.with_imm_characterdata(|text| {
-        match node.parent_node() {
-            Some(parent) if parent.is_element() => {
-                parent.with_imm_element(|elem| {
-                    match elem.tag_name.as_slice() {
+fn serialize_text(text: &JS<Text>) -> ~str {
+    match text.get().characterdata.node.parent_node {
+        Some(ref parent) if parent.is_element() => {
+            let elem: JS<Element> = ElementCast::to(parent);
+            match elem.get().tag_name.as_slice() {
                 "style" | "script" | "xmp" | "iframe" |
                 "noembed" | "noframes" | "plaintext" |
-                        "noscript" if elem.namespace == namespace::HTML => {
-                            text.data.clone()
+                "noscript" if elem.get().namespace == namespace::HTML => {
+                    text.get().characterdata.data.clone()
                 },
-                        _ => escape(text.data, false)
+                _ => escape(text.get().characterdata.data, false)
             }
-               })
-            },
-            _ => escape(text.data, false)
         }
-    })
+        _ => escape(text.get().characterdata.data, false)
+    }
 }
 
-fn serialize_processing_instruction(node: AbstractNode) -> ~str {
-    node.with_imm_processing_instruction(|processing_instruction| {
-        ~"<?" + processing_instruction.target + " " + processing_instruction.characterdata.data + "?>"
-    })
+fn serialize_processing_instruction(processing_instruction: &JS<ProcessingInstruction>) -> ~str {
+    ~"<?" + processing_instruction.get().target + " " + processing_instruction.get().characterdata.data + "?>"
 }
 
-fn serialize_doctype(node: AbstractNode) -> ~str {
-    node.with_imm_doctype(|doctype| {
-        ~"<!DOCTYPE" + doctype.name + ">"
-    })
+fn serialize_doctype(doctype: &JS<DocumentType>) -> ~str {
+    ~"<!DOCTYPE" + doctype.get().name + ">"
 }
 
-fn serialize_elem(node: AbstractNode, open_elements: &mut ~[~str]) -> ~str {
-    node.with_imm_element(|elem| {
-        let mut rv = ~"<" + elem.tag_name;
-        for attr in elem.attrs.iter() {
+fn serialize_elem(elem: &JS<Element>, open_elements: &mut ~[~str]) -> ~str {
+    let mut rv = ~"<" + elem.get().tag_name;
+    for attr in elem.get().attrs.iter() {
         rv.push_str(serialize_attr(attr));
     };
     rv.push_str(">");
-        match elem.tag_name.as_slice() {
-            "pre" | "listing" | "textarea" if
-                elem.namespace == namespace::HTML => {
-                    match node.first_child() {
-                        Some(child) if child.is_text() => {
-                            child.with_imm_characterdata(|text| {
-                                if text.data[0] == 0x0A as u8 {
+    match elem.get().tag_name.as_slice() {
+        "pre" | "listing" | "textarea" if elem.get().namespace == namespace::HTML => {
+            match elem.get().node.first_child {
+                Some(ref child) if child.is_text() => {
+                    let text: JS<CharacterData> = CharacterDataCast::to(child);
+                    if text.get().data[0] == 0x0A as u8 {
                         rv.push_str("\x0A");
                     }
-                            })
                 },
                 _ => {}
             }
         },
         _ => {}
     }
-        if !elem.is_void() {
-            open_elements.push(elem.tag_name.clone());
+    if !elem.get().is_void() {
+        open_elements.push(elem.get().tag_name.clone());
     }
     rv
-    })
 }
 
-fn serialize_attr(attr: &@mut Attr) -> ~str {
-    let attr_name = if attr.namespace == namespace::XML {
-        ~"xml:" + attr.local_name.clone()
-    } else if attr.namespace == namespace::XMLNS &&
-        attr.local_name.as_slice() == "xmlns" {
+fn serialize_attr(attr: &JS<Attr>) -> ~str {
+    let attr_name = if attr.get().namespace == namespace::XML {
+        ~"xml:" + attr.get().local_name.clone()
+    } else if attr.get().namespace == namespace::XMLNS &&
+        attr.get().local_name.as_slice() == "xmlns" {
         ~"xmlns"
-    } else if attr.namespace == namespace::XMLNS {
-        ~"xmlns:" + attr.local_name.clone()
-    } else if attr.namespace == namespace::XLink {
-        ~"xlink:" + attr.local_name.clone()
+    } else if attr.get().namespace == namespace::XMLNS {
+        ~"xmlns:" + attr.get().local_name.clone()
+    } else if attr.get().namespace == namespace::XLink {
+        ~"xlink:" + attr.get().local_name.clone()
     } else {
-        attr.name.clone()
+        attr.get().name.clone()
     };
-    ~" " + attr_name + "=\"" + escape(attr.value, true) + "\""
+    ~" " + attr_name + "=\"" + escape(attr.get().value, true) + "\""
 }
 
 fn escape(string: &str, attr_mode: bool) -> ~str {

src/components/script/dom/htmlsourceelement.rs

@@ -3,27 +3,40 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLSourceElementBinding;
+use dom::bindings::codegen::InheritTypes::HTMLSourceElementDerived;
+use dom::bindings::js::JS;
 use dom::bindings::utils::ErrorResult;
-use dom::document::AbstractDocument;
+use dom::document::Document;
 use dom::element::HTMLSourceElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLSourceElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLSourceElementDerived for EventTarget {
+    fn is_htmlsourceelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLSourceElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLSourceElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLSourceElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLSourceElement {
         HTMLSourceElement {
             htmlelement: HTMLElement::new_inherited(HTMLSourceElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLSourceElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLSourceElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLSourceElement> {
+        let element = HTMLSourceElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLSourceElementBinding::Wrap)
     }
 }
 

src/components/script/dom/htmlspanelement.rs

@@ -3,25 +3,38 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::HTMLSpanElementBinding;
-use dom::document::AbstractDocument;
+use dom::bindings::codegen::InheritTypes::HTMLSpanElementDerived;
+use dom::bindings::js::JS;
+use dom::document::Document;
 use dom::element::HTMLSpanElementTypeId;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
-use dom::node::{AbstractNode, Node};
+use dom::node::{Node, ElementNodeTypeId};
 use servo_util::str::DOMString;
 
+#[deriving(Encodable)]
 pub struct HTMLSpanElement {
     htmlelement: HTMLElement
 }
 
+impl HTMLSpanElementDerived for EventTarget {
+    fn is_htmlspanelement(&self) -> bool {
+        match self.type_id {
+            NodeTargetTypeId(ElementNodeTypeId(HTMLSpanElementTypeId)) => true,
+            _ => false
+        }
+    }
+}
+
 impl HTMLSpanElement {
-    pub fn new_inherited(localName: DOMString, document: AbstractDocument) -> HTMLSpanElement {
+    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLSpanElement {
         HTMLSpanElement {
             htmlelement: HTMLElement::new_inherited(HTMLSpanElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: AbstractDocument) -> AbstractNode {
-        let element = HTMLSpanElement::new_inherited(localName, document);
-        Node::reflect_node(@mut element, document, HTMLSpanElementBinding::Wrap)
+    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLSpanElement> {
+        let element = HTMLSpanElement::new_inherited(localName, document.clone());
+        Node::reflect_node(~element, document, HTMLSpanElementBinding::Wrap)
     }
 }