Add StyleChangeState to get rid of a bunch of static state in the render tree.

Source/WebCore/rendering/RenderBox.h

Index: Source/WebCore/rendering/RenderBox.h
diff --git a/Source/WebCore/rendering/RenderBox.h b/Source/WebCore/rendering/RenderBox.h
index 61e83de7c1e49800fd3e94abfe2b8691615b1f7c..c5b8428e2208a52fcac8f0fc0f264319796ef89c 100644
--- a/Source/WebCore/rendering/RenderBox.h
+++ b/Source/WebCore/rendering/RenderBox.h
@@ -589,9 +589,9 @@ public:
 protected:
     virtual void willBeDestroyed();
 
-    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle);
-    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle);
-    virtual void updateFromStyle() OVERRIDE;
+    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle, StyleChangeState&) OVERRIDE;
+    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle, const StyleChangeState&) OVERRIDE;
+    virtual void updateFromStyle(const StyleChangeState&) OVERRIDE;
 
     LayoutRect backgroundPaintedExtent() const;
     virtual bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const;
@@ -689,10 +689,6 @@ protected:
 
     // Our overflow information.
     OwnPtr<RenderOverflow> m_overflow;
-
-private:
-    // Used to store state between styleWillChange and styleDidChange
-    static bool s_hadOverflowClip;

[eseidel, 2013/04/05 01:50:36]

This scares me! I can't believe we had this.

 };
 
 inline RenderBox* toRenderBox(RenderObject* object)