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

Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp

Index: Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
diff --git a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
index 7f329c3b8029009541aa231f7f449120e43e28c1..7c3b698c419feb6a30c3aa1e5a9d3ad7c3b94fd8 100644
--- a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
+++ b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
@@ -2128,24 +2128,24 @@ void CompositedDeprecatedPaintLayerMapping::doPaintTask(const GraphicsLayerPaint
         // FIXME: Combine similar code here and LayerClipRecorder.
         dirtyRect.intersect(paintInfo.localClipRectForSquashedLayer);
         {
-            OwnPtr<DisplayItem> clipDisplayItem = ClipDisplayItem::create(*this, DisplayItem::ClipLayerOverflowControls, dirtyRect);
+            ClipDisplayItem clipDisplayItem(*this, DisplayItem::ClipLayerOverflowControls, dirtyRect);
             if (context->displayItemList()) {
                 ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
                 if (!context->displayItemList()->displayItemConstructionIsDisabled())
-                    context->displayItemList()->add(clipDisplayItem.release());
+                    context->displayItemList()->add(clipDisplayItem);
             } else {
-                clipDisplayItem->replay(*context);
+                clipDisplayItem.replay(*context);
             }
         }
         DeprecatedPaintLayerPainter(*paintInfo.paintLayer).paintLayer(context, paintingInfo, paintLayerFlags);
         {
-            OwnPtr<DisplayItem> endClipDisplayItem = EndClipDisplayItem::create(*this, DisplayItem::clipTypeToEndClipType(DisplayItem::ClipLayerOverflowControls));
+            EndClipDisplayItem endClipDisplayItem(*this, DisplayItem::clipTypeToEndClipType(DisplayItem::ClipLayerOverflowControls));
             if (context->displayItemList()) {
                 ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
                 if (!context->displayItemList()->displayItemConstructionIsDisabled())
-                    context->displayItemList()->add(endClipDisplayItem.release());
+                    context->displayItemList()->add(endClipDisplayItem);
             } else {
-                endClipDisplayItem->replay(*context);
+                endClipDisplayItem.replay(*context);
             }
         }
     }