layout: Switch display list building from bottom-up to top-down.

This eliminates a lot of allocations and O(n^2) behavior.

1 files changed, 1 insertions, 7 deletions

diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index def1f7bf8a7..1dd4b386ad8 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -34,7 +34,7 @@ use floats::Floats;
 use flow_list::{FlowList, FlowListIterator, MutFlowListIterator};
 use flow_ref::{self, FlowRef, WeakFlowRef};
 use fragment::{Fragment, FragmentBorderBoxIterator, Overflow, SpecificFragmentInfo};
-use gfx::display_list::{ClippingRegion, DisplayListEntry, StackingContext, StackingContextId};
+use gfx::display_list::{ClippingRegion, StackingContext, StackingContextId};
 use gfx_traits::{LayerId, LayerType};
 use incremental::{RECONSTRUCT_FLOW, REFLOW, REFLOW_OUT_OF_FLOW, REPAINT, RestyleDamage};
 use inline::InlineFlow;
@@ -957,9 +957,6 @@ pub struct BaseFlow {
     /// per-stacking-context.
     pub stacking_relative_position_of_display_port: Rect<Au>,
 
-    /// The results of display list building for this flow.
-    pub display_list_building_result: Option<Vec<DisplayListEntry>>,
-
     /// The writing mode for this flow.
     pub writing_mode: WritingMode,
 
@@ -1129,7 +1126,6 @@ impl BaseFlow {
             block_container_writing_mode: writing_mode,
             block_container_explicit_block_size: None,
             absolute_cb: ContainingBlockLink::new(),
-            display_list_building_result: None,
             early_absolute_position_info: EarlyAbsolutePositionInfo::new(writing_mode),
             late_absolute_position_info: LateAbsolutePositionInfo::new(),
             clip: ClippingRegion::max(),
@@ -1147,8 +1143,6 @@ impl BaseFlow {
             children: children,
             restyle_damage: self.restyle_damage | REPAINT | REFLOW_OUT_OF_FLOW | REFLOW,
             parallel: FlowParallelInfo::new(),
-            display_list_building_result: None,
-
             floats: self.floats.clone(),
             abs_descendants: self.abs_descendants.clone(),
             absolute_cb: self.absolute_cb.clone(),