Auto merge of #9706 - mrobinson:remove-parallel-display-list-building, r=pcwalton

Remove parallel display list construction

Parallel display list construction hasn't been shown to give any
performance gains. It is also incompatible with the current flat display
list implementation. Once flat display lists have landed, we can explore
possible benefits of parallel construction once again.

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1 files changed, 1 insertions, 13 deletions

diff --git a/components/layout/layout_thread.rs b/components/layout/layout_thread.rs
index e1e163acb39..b574e2d62fd 100644
--- a/components/layout/layout_thread.rs
+++ b/components/layout/layout_thread.rs
@@ -860,19 +860,7 @@ impl LayoutThread {
             flow::mut_base(flow_ref::deref_mut(layout_root)).clip =
                 ClippingRegion::from_rect(&data.page_clip_rect);
 
-            match (&mut self.parallel_traversal, opts::get().parallel_display_list_building) {
-                (&mut Some(ref mut traversal), true) => {
-                    parallel::build_display_list_for_subtree(layout_root,
-                                                             metadata,
-                                                             sender,
-                                                             shared_layout_context,
-                                                             traversal);
-                }
-                _ => {
-                    sequential::build_display_list_for_subtree(layout_root,
-                                                               shared_layout_context);
-                }
-            }
+            sequential::build_display_list_for_subtree(layout_root, shared_layout_context);
 
             if data.goal == ReflowGoal::ForDisplay {
                 debug!("Done building display list.");