Turn styleWillChange |newStyle| into a reference

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 086b62f41f550b522f08ea2755883265f58ee352..c72e6809b4c801217dec58cbdc55058f8be3e4a0 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -997,9 +997,11 @@ public:
 protected:
     inline bool layerCreationAllowedForSubtree() const;
 
-    // Overrides should call the superclass at the end
-    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle);
-    // Overrides should call the superclass at the start
+    // Overrides should call the superclass at the end. m_style will be 0 the first time
+    // this function will be called.
+    virtual void styleWillChange(StyleDifference, const RenderStyle& newStyle);
+    // Overrides should call the superclass at the start. |oldStyle| will be 0 the first
+    // time this function is called.
     virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle);
     void propagateStyleToAnonymousChildren(bool blockChildrenOnly = false);