Eliminate HAS_CHANGED in favor of explicit RestyleDamage.

components/layout/traversal.rs

@@ -118,16 +118,13 @@ impl<'lc, N> DomTraversalContext<N> for RecalcStyleAndConstructFlows<'lc>
             return false;
         }
 
-        // If this node has been marked as damaged in some way, we need to
-        // traverse it for layout.
-        if child.has_changed() {
-            return true;
-        }
-
         match child.as_element() {
-            Some(el) => el.styling_mode() != StylingMode::Stop,
-            // Aside from the has_changed case above, we want to traverse non-element children
-            // in two additional cases:
+            // Elements should be traversed if they need styling or flow construction.
+            Some(el) => el.styling_mode() != StylingMode::Stop ||
+                        el.as_node().to_threadsafe().restyle_damage() != RestyleDamage::empty(),
+
+            // Text nodes never need styling. However, there are two cases they may need
+            // flow construction:
             // (1) They child doesn't yet have layout data (preorder traversal initializes it).
             // (2) The parent element has restyle damage (so the text flow also needs fixup).
             None => child.get_raw_data().is_none() ||

components/script/dom/node.rs

@@ -143,8 +143,6 @@ bitflags! {
     pub flags NodeFlags: u8 {
         #[doc = "Specifies whether this node is in a document."]
         const IS_IN_DOC = 0x01,
-        #[doc = "Specifies whether this node _must_ be reflowed regardless of style differences."]
-        const HAS_CHANGED = 0x02,
         #[doc = "Specifies whether this node needs style recalc on next reflow."]
         const IS_DIRTY = 0x04,
         #[doc = "Specifies whether this node has descendants (inclusive of itself) which \
@@ -169,7 +167,7 @@ bitflags! {
 
 impl NodeFlags {
     pub fn new() -> NodeFlags {
-        HAS_CHANGED | IS_DIRTY | HAS_DIRTY_DESCENDANTS
+        IS_DIRTY | HAS_DIRTY_DESCENDANTS
     }
 }
 
@@ -422,14 +420,6 @@ impl Node {
         self.flags.set(flags);
     }
 
-    pub fn has_changed(&self) -> bool {
-        self.get_flag(HAS_CHANGED)
-    }
-
-    pub fn set_has_changed(&self, state: bool) {
-        self.set_flag(HAS_CHANGED, state)
-    }
-
     pub fn is_dirty(&self) -> bool {
         self.get_flag(IS_DIRTY)
     }

components/script/layout_wrapper.rs

@@ -36,7 +36,7 @@ use dom::bindings::js::LayoutJS;
 use dom::characterdata::LayoutCharacterDataHelpers;
 use dom::document::{Document, LayoutDocumentHelpers, PendingRestyle};
 use dom::element::{Element, LayoutElementHelpers, RawLayoutElementHelpers};
-use dom::node::{CAN_BE_FRAGMENTED, DIRTY_ON_VIEWPORT_SIZE_CHANGE, HAS_CHANGED, HAS_DIRTY_DESCENDANTS, IS_DIRTY};
+use dom::node::{CAN_BE_FRAGMENTED, DIRTY_ON_VIEWPORT_SIZE_CHANGE, HAS_DIRTY_DESCENDANTS, IS_DIRTY};
 use dom::node::{LayoutNodeHelpers, Node};
 use dom::text::Text;
 use gfx_traits::ByteIndex;
@@ -62,7 +62,7 @@ use style::computed_values::display;
 use style::context::SharedStyleContext;
 use style::data::ElementData;
 use style::dom::{LayoutIterator, NodeInfo, OpaqueNode, PresentationalHintsSynthetizer, TElement, TNode};
-use style::dom::{TRestyleDamage, UnsafeNode};
+use style::dom::UnsafeNode;
 use style::element_state::*;
 use style::properties::{ComputedValues, PropertyDeclarationBlock};
 use style::selector_impl::{NonTSPseudoClass, PseudoElement, RestyleDamage, ServoSelectorImpl};
@@ -259,12 +259,7 @@ impl<'ln> LayoutNode for ServoLayoutNode<'ln> {
         self.get_jsmanaged().take_style_and_layout_data()
     }
 
-    fn has_changed(&self) -> bool {
-        unsafe { self.node.get_flag(HAS_CHANGED) }
-    }
-
     unsafe fn clear_dirty_bits(&self) {
-        self.node.set_flag(HAS_CHANGED, false);
         self.node.set_flag(IS_DIRTY, false);
         self.node.set_flag(HAS_DIRTY_DESCENDANTS, false);
     }
@@ -335,8 +330,8 @@ impl<'ln> ServoLayoutNode<'ln> {
     }
 
     fn debug_str(self) -> String {
-        format!("{:?}: changed={} dirty={} dirty_descendants={}",
-                self.script_type_id(), self.has_changed(),
+        format!("{:?}: dirty={} dirty_descendants={}",
+                self.script_type_id(),
                 self.as_element().map_or(false, |el| el.deprecated_dirty_bit_is_set()),
                 self.as_element().map_or(false, |el| el.has_dirty_descendants()))
     }
@@ -453,7 +448,7 @@ impl<'le> TElement for ServoLayoutElement<'le> {
     }
 
     fn set_restyle_damage(self, damage: RestyleDamage) {
-        self.get_partial_layout_data().unwrap().borrow_mut().restyle_damage = damage;
+        self.get_partial_layout_data().unwrap().borrow_mut().restyle_damage |= damage;
     }
 
     #[inline]
@@ -879,9 +874,7 @@ impl<'ln> ThreadSafeLayoutNode for ServoThreadSafeLayoutNode<'ln> {
     }
 
     fn restyle_damage(self) -> RestyleDamage {
-        if self.node.has_changed() {
-            RestyleDamage::rebuild_and_reflow()
-        } else if self.is_text_node() {
+        if self.is_text_node() {
             let parent = self.node.parent_node().unwrap().as_element().unwrap();
             let parent_data = parent.get_partial_layout_data().unwrap().borrow();
             parent_data.restyle_damage

components/script_layout_interface/lib.rs

@@ -51,6 +51,7 @@ use libc::c_void;
 use std::sync::atomic::AtomicIsize;
 use style::atomic_refcell::AtomicRefCell;
 use style::data::ElementData;
+use style::dom::TRestyleDamage;
 use style::selector_impl::RestyleDamage;
 
 pub struct PartialPersistentLayoutData {
@@ -71,7 +72,10 @@ impl PartialPersistentLayoutData {
     pub fn new() -> Self {
         PartialPersistentLayoutData {
             style_data: ElementData::new(),
-            restyle_damage: RestyleDamage::empty(),
+            // FIXME(bholley): This is needed for now to make sure we do frame
+            // construction after initial styling. This will go away shortly when
+            // we move restyle damage into the style system.
+            restyle_damage: RestyleDamage::rebuild_and_reflow(),
             parallel: DomParallelInfo::new(),
         }
     }

components/script_layout_interface/wrapper_traits.rs

@@ -86,8 +86,6 @@ pub trait LayoutNode: GetLayoutData + TNode {
     unsafe fn init_style_and_layout_data(&self, data: OpaqueStyleAndLayoutData);
     unsafe fn take_style_and_layout_data(&self) -> OpaqueStyleAndLayoutData;
 
-    fn has_changed(&self) -> bool;
-
     unsafe fn clear_dirty_bits(&self);
 
     fn rev_children(self) -> LayoutIterator<ReverseChildrenIterator<Self>> {