Disable clipping on root scroller's ancestors.

third_party/WebKit/Source/core/paint/PaintLayer.h

Index: third_party/WebKit/Source/core/paint/PaintLayer.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.h b/third_party/WebKit/Source/core/paint/PaintLayer.h
index bf0330163de5eaf2444b49d99f3ec0e0336e1455..368f4fd77b08dcfd5b0ee2ec9e1f29178c80bb43 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.h
@@ -585,7 +585,7 @@ public:
 
     void updateAncestorOverflowLayer(const PaintLayer* ancestorOverflowLayer) { m_ancestorOverflowLayer = ancestorOverflowLayer; }
     void updateAncestorDependentCompositingInputs(const AncestorDependentCompositingInputs&, const RareAncestorDependentCompositingInputs&, bool hasAncestorWithClipPath);
-    void updateDescendantDependentCompositingInputs(bool hasDescendantWithClipPath, bool hasNonIsolatedDescendantWithBlendMode);
+    void updateDescendantDependentCompositingInputs(bool hasDescendantWithClipPath, bool hasNonIsolatedDescendantWithBlendMode, bool hasRootScrollerAsDescendant);
     void didUpdateCompositingInputs();
 
     IntRect clippedAbsoluteBoundingBox() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_ancestorDependentCompositingInputs.clippedAbsoluteBoundingBox; }
@@ -602,6 +602,8 @@ public:
     bool hasDescendantWithClipPath() const { ASSERT(!m_needsDescendantDependentCompositingInputsUpdate); return m_hasDescendantWithClipPath; }
     bool hasNonIsolatedDescendantWithBlendMode() const;
 
+    bool hasRootScrollerAsDescendant() const { ASSERT(!m_needsDescendantDependentCompositingInputsUpdate); return m_hasRootScrollerAsDescendant; }
+
     bool lostGroupedMapping() const { ASSERT(isAllowedToQueryCompositingState()); return m_lostGroupedMapping; }
     void setLostGroupedMapping(bool b) { m_lostGroupedMapping = b; }
 
@@ -858,6 +860,7 @@ private:
     unsigned m_hasDescendantWithClipPath : 1;
     unsigned m_hasNonIsolatedDescendantWithBlendMode : 1;
     unsigned m_hasAncestorWithClipPath : 1;
+    unsigned m_hasRootScrollerAsDescendant : 1;
 
     LayoutBoxModelObject* m_layoutObject;