Rework compositor touch hit testing

Source/core/rendering/RenderView.h

Index: Source/core/rendering/RenderView.h
diff --git a/Source/core/rendering/RenderView.h b/Source/core/rendering/RenderView.h
index 340a3e294297adac9791d742c220f29c834ad45b..e09de053b1984e1bbf13a5352bfe477b0c800637 100644
--- a/Source/core/rendering/RenderView.h
+++ b/Source/core/rendering/RenderView.h
@@ -37,6 +37,9 @@ class RenderLazyBlock;
 class RenderQuote;
 class RenderWidget;
 
+// The root of the render tree, corresponding to the CSS initial containing block.
+// It's dimensions match that of the viewport, and it is always at position (0,0)
+// relative to the document (and so isn't necessarily in view).
 class RenderView FINAL : public RenderBlock {
 public:
     explicit RenderView(Document*);
@@ -203,6 +206,7 @@ protected:
     virtual const RenderObject* pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap&) const OVERRIDE;
     virtual void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const;
     virtual bool requiresColumns(int desiredColumnCount) const OVERRIDE;
+    virtual void computeOwnHitTestRects(Vector<IntRect>&, const LayoutPoint& layerOffset) const OVERRIDE;
     
 private:
     bool initializeLayoutState(LayoutState&);