Auto merge of #15805 - emilio:reposition, r=glennw

layout_thread: Also reposition elements when reflowing all nodes.

<!-- Reviewable:start -->
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/15805)
<!-- Reviewable:end -->

components/layout_thread/lib.rs

@@ -496,8 +496,6 @@ impl LayoutThread {
     // Create a layout context for use in building display lists, hit testing, &c.
     fn build_layout_context(&self,
                             rw_data: &LayoutThreadData,
-                            screen_size_changed: bool,
-                            goal: ReflowGoal,
                             request_images: bool)
                             -> LayoutContext {
         let thread_local_style_context_creation_data =
@@ -506,9 +504,7 @@ impl LayoutThread {
         LayoutContext {
             style_context: SharedStyleContext {
                 viewport_size: self.viewport_size.clone(),
-                screen_size_changed: screen_size_changed,
                 stylist: rw_data.stylist.clone(),
-                goal: goal,
                 running_animations: self.running_animations.clone(),
                 expired_animations: self.expired_animations.clone(),
                 error_reporter: self.error_reporter.clone(),
@@ -1035,9 +1031,6 @@ impl LayoutThread {
                             Au::from_f32_px(constraints.size.height))
             });
 
-        // Handle conditions where the entire flow tree is invalid.
-        let mut needs_dirtying = false;
-
         let viewport_size_changed = self.viewport_size != old_viewport_size;
         if viewport_size_changed {
             if let Some(constraints) = rw_data.stylist.viewport_constraints() {
@@ -1071,9 +1064,9 @@ impl LayoutThread {
         }
 
         // If the entire flow tree is invalid, then it will be reflowed anyhow.
-        needs_dirtying |= Arc::get_mut(&mut rw_data.stylist).unwrap().update(&data.document_stylesheets,
+        let needs_dirtying = Arc::get_mut(&mut rw_data.stylist).unwrap().update(&data.document_stylesheets,
-                                                                             Some(&*UA_STYLESHEETS),
+                                                                                 Some(&*UA_STYLESHEETS),
-                                                                             data.stylesheets_changed);
+                                                                                 data.stylesheets_changed);
         let needs_reflow = viewport_size_changed && !needs_dirtying;
         if needs_dirtying {
             if let Some(mut d) = element.mutate_data() {
@@ -1119,10 +1112,7 @@ impl LayoutThread {
         }
 
         // Create a layout context for use throughout the following passes.
-        let mut layout_context = self.build_layout_context(&*rw_data,
+        let mut layout_context = self.build_layout_context(&*rw_data, true);
-                                                           viewport_size_changed,
-                                                           data.reflow_info.goal,
-                                                           true);
 
         // NB: Type inference falls apart here for some reason, so we need to be very verbose. :-(
         let traversal_driver = if self.parallel_flag && self.parallel_traversal.is_some() {
@@ -1350,10 +1340,7 @@ impl LayoutThread {
             page_clip_rect: max_rect(),
         };
 
-        let mut layout_context = self.build_layout_context(&*rw_data,
+        let mut layout_context = self.build_layout_context(&*rw_data, false);
-                                                           false,
-                                                           reflow_info.goal,
-                                                           false);
 
         if let Some(mut root_flow) = self.root_flow.clone() {
             // Perform an abbreviated style recalc that operates without access to the DOM.
@@ -1386,10 +1373,7 @@ impl LayoutThread {
             page_clip_rect: max_rect(),
         };
 
-        let mut layout_context = self.build_layout_context(&*rw_data,
+        let mut layout_context = self.build_layout_context(&*rw_data, false);
-                                                           false,
-                                                           reflow_info.goal,
-                                                           false);
 
         // No need to do a style recalc here.
         if self.root_flow.is_none() {
@@ -1516,7 +1500,9 @@ impl LayoutThread {
 
     fn reflow_all_nodes(flow: &mut Flow) {
         debug!("reflowing all nodes!");
-        flow::mut_base(flow).restyle_damage.insert(REPAINT | STORE_OVERFLOW | REFLOW);
+        flow::mut_base(flow)
+            .restyle_damage
+            .insert(REPAINT | STORE_OVERFLOW | REFLOW | REPOSITION);
 
         for child in flow::child_iter_mut(flow) {
             LayoutThread::reflow_all_nodes(child);

components/style/context.rs

@@ -64,15 +64,9 @@ pub struct SharedStyleContext {
     /// The current viewport size.
     pub viewport_size: Size2D<Au>,
 
-    /// Screen sized changed?
-    pub screen_size_changed: bool,
-
     /// The CSS selector stylist.
     pub stylist: Arc<Stylist>,
 
-    /// Why is this reflow occurring
-    pub goal: ReflowGoal,
-
     /// The animations that are currently running.
     pub running_animations: Arc<RwLock<HashMap<OpaqueNode, Vec<Animation>>>>,
 

ports/geckolib/glue.rs

@@ -20,7 +20,7 @@ use std::fmt::Write;
 use std::ptr;
 use std::sync::{Arc, Mutex};
 use style::arc_ptr_eq;
-use style::context::{QuirksMode, ReflowGoal, SharedStyleContext, StyleContext};
+use style::context::{QuirksMode, SharedStyleContext, StyleContext};
 use style::context::{ThreadLocalStyleContext, ThreadLocalStyleContextCreationInfo};
 use style::data::{ElementData, ElementStyles, RestyleData};
 use style::dom::{ShowSubtreeData, TElement, TNode};
@@ -164,8 +164,6 @@ fn create_shared_context(per_doc_data: &PerDocumentStyleDataImpl) -> SharedStyle
     SharedStyleContext {
         // FIXME (bug 1303229): Use the actual viewport size here
         viewport_size: Size2D::new(Au(0), Au(0)),
-        screen_size_changed: false,
-        goal: ReflowGoal::ForScriptQuery,
         stylist: per_doc_data.stylist.clone(),
         running_animations: per_doc_data.running_animations.clone(),
         expired_animations: per_doc_data.expired_animations.clone(),