Fix paint invalidation rect tracking within composited scrolling layers.

Source/core/layout/LayoutBoxModelObject.cpp

Index: Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/Source/core/layout/LayoutBoxModelObject.cpp b/Source/core/layout/LayoutBoxModelObject.cpp
index 1cf99d2bc82979715fcac0c08540c58d41ba5ed1..294d41b221e6da52ec8627cadb262772bbc2d8ec 100644
--- a/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/Source/core/layout/LayoutBoxModelObject.cpp
@@ -118,6 +118,11 @@ LayoutBoxModelObject::LayoutBoxModelObject(ContainerNode* node)
 {
 }
 
+bool LayoutBoxModelObject::usesCompositedScrolling() const
+{
+    return hasOverflowClip() && hasLayer() && layer()->scrollableArea()->usesCompositedScrolling();
+}
+
 LayoutBoxModelObject::~LayoutBoxModelObject()
 {
     // Our layer should have been destroyed and cleared by now