Reland "Avoid layout/full-repaint on view height change if possible"

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 cc98c36da0410c8b215f096c7bccf0ad5212311e..c18ac0938817c4cc168ed6e187409ff2084343cd 100644
--- a/Source/core/rendering/RenderView.h
+++ b/Source/core/rendering/RenderView.h
@@ -207,6 +207,8 @@ public:
     void disableLayoutState() { m_layoutStateDisableCount++; }
     void enableLayoutState() { ASSERT(m_layoutStateDisableCount > 0); m_layoutStateDisableCount--; }
 
+    bool trySimplifiedLayoutOnHeightChange();
+
 private:
     virtual void mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0) const OVERRIDE;
     virtual const RenderObject* pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap&) const OVERRIDE;