Revert of Revert "Disable local background equivalence when we have a box shadow due to painting bug

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
index f4b697bd895f7b7d4ba53b1babfd3342e5520374..d35fc7fd00589fa1d285cc7816a2ed03aad14416 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp
@@ -127,6 +127,12 @@
   // TODO(flackr): When we correctly clip the scrolling contents layer we can
   // paint locally equivalent backgrounds into it. https://crbug.com/645957
   if (!style()->hasAutoClip())
+    return BackgroundPaintInGraphicsLayer;
+
+  // TODO(flackr): Remove this when box shadows are still painted correctly when
+  // painting into the composited scrolling contents layer.
+  // https://crbug.com/646464
+  if (style()->boxShadow())
     return BackgroundPaintInGraphicsLayer;
 
   // Assume optimistically that the background can be painted in the scrolling