Implement PaintLayer::scrollsWithViewport for SPv2.

third_party/WebKit/Source/core/paint/ObjectPaintProperties.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/ObjectPaintProperties.h"
 
 namespace blink {
 
 ObjectPaintProperties::PropertyTreeStateWithOffset
 ObjectPaintProperties::contentsProperties() const {
   ObjectPaintProperties::PropertyTreeStateWithOffset propertiesWithOffset =
       *localBorderBoxProperties();
   if (svgLocalToBorderBoxTransform()) {
     propertiesWithOffset.propertyTreeState.setTransform(
         svgLocalToBorderBoxTransform());
     // There's no paint offset for the contents because
     // svgLocalToBorderBoxTransform bakes in the paint offset.
     propertiesWithOffset.paintOffset = LayoutPoint();
   } else if (scrollTranslation()) {
     propertiesWithOffset.propertyTreeState.setTransform(scrollTranslation());
   }
 
+  if (scroll())
+    propertiesWithOffset.propertyTreeState.setScroll(scroll());
+
   if (overflowClip())
     propertiesWithOffset.propertyTreeState.setClip(overflowClip());
   else if (cssClip())
     propertiesWithOffset.propertyTreeState.setClip(cssClip());
 
   // TODO(chrishtr): cssClipFixedPosition needs to be handled somehow.
 
   return propertiesWithOffset;
 }
 
 }  // namespace blink