[Slimming Paint] Blink-side contiguous allocation of display items.

Source/core/paint/CompositingRecorder.cpp

Index: Source/core/paint/CompositingRecorder.cpp
diff --git a/Source/core/paint/CompositingRecorder.cpp b/Source/core/paint/CompositingRecorder.cpp
index 8d68e46828114ae148889c7e4f7d0ed0663eb0eb..0afcec69d4d35efa98d9e308fbeb94dcfc0dc7d8 100644
--- a/Source/core/paint/CompositingRecorder.cpp
+++ b/Source/core/paint/CompositingRecorder.cpp
@@ -27,26 +27,26 @@ CompositingRecorder::~CompositingRecorder()
 
 void CompositingRecorder::beginCompositing(GraphicsContext& graphicsContext, const DisplayItemClientWrapper& client, const SkXfermode::Mode xferMode, const float opacity, const FloatRect* bounds, ColorFilter colorFilter)
 {
+    BeginCompositingDisplayItem beginCompositingDisplayItem(client, xferMode, opacity, bounds, colorFilter);
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(graphicsContext.displayItemList());
         if (graphicsContext.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        graphicsContext.displayItemList()->add(BeginCompositingDisplayItem::create(client, xferMode, opacity, bounds, colorFilter));
+        graphicsContext.displayItemList()->add(beginCompositingDisplayItem);
     } else {
-        BeginCompositingDisplayItem beginCompositingDisplayItem(client, xferMode, opacity, bounds, colorFilter);
         beginCompositingDisplayItem.replay(graphicsContext);
     }
 }
 
 void CompositingRecorder::endCompositing(GraphicsContext& graphicsContext, const DisplayItemClientWrapper& client)
 {
+    EndCompositingDisplayItem endCompositingDisplayItem(client);
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(graphicsContext.displayItemList());
         if (graphicsContext.displayItemList()->displayItemConstructionIsDisabled())
             return;
-        graphicsContext.displayItemList()->add(EndCompositingDisplayItem::create(client));
+        graphicsContext.displayItemList()->add(endCompositingDisplayItem);
     } else {
-        EndCompositingDisplayItem endCompositingDisplayItem(client);
         endCompositingDisplayItem.replay(graphicsContext);
     }
 }