Ignore overflow clip on root layer if HitTestRequest::IgnoreClipping is set.

Source/core/paint/DeprecatedPaintLayerClipper.h

Index: Source/core/paint/DeprecatedPaintLayerClipper.h
diff --git a/Source/core/paint/DeprecatedPaintLayerClipper.h b/Source/core/paint/DeprecatedPaintLayerClipper.h
index d6c987d13d03e80c0e0c3b65af318a19b1aa639c..707e58e453dbab3758fe9d0fcd74d92f66efe60f 100644
--- a/Source/core/paint/DeprecatedPaintLayerClipper.h
+++ b/Source/core/paint/DeprecatedPaintLayerClipper.h
@@ -65,6 +65,7 @@ public:
         , cacheSlot(slot)
         , subPixelAccumulation(accumulation)
         , respectOverflowClip(slot == PaintingClipRectsIgnoringOverflowClip ? IgnoreOverflowClip : RespectOverflowClip)
+        , respectOverflowClipForViewport(slot == RootRelativeClipRectsIgnoringViewportClip ? IgnoreOverflowClip : RespectOverflowClip)
     {
     }
 
@@ -91,6 +92,7 @@ private:
     ClipRectsCacheSlot cacheSlot;
     LayoutSize subPixelAccumulation;
     ShouldRespectOverflowClip respectOverflowClip;
+    ShouldRespectOverflowClip respectOverflowClipForViewport;
 };
 
 class DeprecatedPaintLayerClipper {
@@ -139,6 +141,8 @@ private:
         return *m_cache;
     }
 
+    bool shouldRespectOverflowClip(const ClipRectsContext&) const;
+
     // FIXME: Could this be a LayoutBox?
     LayoutBoxModelObject& m_layoutObject;
     mutable OwnPtr<ClipRectsCache> m_cache;