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

Source/platform/graphics/paint/CompositingDisplayItem.cpp

Index: Source/platform/graphics/paint/CompositingDisplayItem.cpp
diff --git a/Source/platform/graphics/paint/CompositingDisplayItem.cpp b/Source/platform/graphics/paint/CompositingDisplayItem.cpp
index 5296d016fdd1fbd7da2ec9d501705023a9715725..508ffdfa3e309d94e9495592a102638c8d56f0fc 100644
--- a/Source/platform/graphics/paint/CompositingDisplayItem.cpp
+++ b/Source/platform/graphics/paint/CompositingDisplayItem.cpp
@@ -7,6 +7,7 @@
 
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/paint/DisplayItems.h"
 #include "platform/graphics/skia/SkiaUtils.h"
 #include "public/platform/WebDisplayItemList.h"
 
@@ -23,6 +24,14 @@ void BeginCompositingDisplayItem::appendToWebDisplayItemList(WebDisplayItemList*
     list->appendCompositingItem(m_opacity, m_xferMode, m_hasBounds ? &bounds : nullptr, GraphicsContext::WebCoreColorFilterToSkiaColorFilter(m_colorFilter).get());
 }
 
+void BeginCompositingDisplayItem::appendByMoving(DisplayItems& destination)
+{
+    FloatRect* bounds = m_hasBounds ? &m_bounds : nullptr;
+    destination.emplaceBack<BeginCompositingDisplayItem>(
+        DisplayItemClientWrapperHelper(*this),
+        m_xferMode, m_opacity, bounds, m_colorFilter);
+}
+
 #ifndef NDEBUG
 void BeginCompositingDisplayItem::dumpPropertiesAsDebugString(WTF::StringBuilder& stringBuilder) const
 {
@@ -43,4 +52,10 @@ void EndCompositingDisplayItem::appendToWebDisplayItemList(WebDisplayItemList* l
     list->appendEndCompositingItem();
 }
 
+void EndCompositingDisplayItem::appendByMoving(DisplayItems& destination)
+{
+    destination.emplaceBack<EndCompositingDisplayItem>(
+        DisplayItemClientWrapperHelper(*this));
+}
+
 } // namespace blink