Smaller vtbls in RenderObject

Source/core/rendering/RenderGrid.h

Index: Source/core/rendering/RenderGrid.h
diff --git a/Source/core/rendering/RenderGrid.h b/Source/core/rendering/RenderGrid.h
index a8bc201c836065cb1c03c4b84abb65d08bab6ec7..d946666450b98e4a1f47cb680ad6a3be31aa31ac 100644
--- a/Source/core/rendering/RenderGrid.h
+++ b/Source/core/rendering/RenderGrid.h
@@ -61,7 +61,7 @@ public:
     bool gridIsDirty() const { return m_gridIsDirty; }
 
 private:
-    virtual bool isRenderGrid() const override { return true; }
+    virtual bool isOfType(RenderObjectType type) const override { return type == RenderObjectRenderGrid || RenderBlock::isOfType(type); }
     virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const override;
     virtual void computePreferredLogicalWidths() override;