Improve RAII of StyleResolverState.

Source/core/css/resolver/StyleResolverState.h

Index: Source/core/css/resolver/StyleResolverState.h
diff --git a/Source/core/css/resolver/StyleResolverState.h b/Source/core/css/resolver/StyleResolverState.h
index 5665c86c15c2331ba4f5a0ef10dc2e241c9e2465..12d7a80a45a85e69e316aa5d3b8c149400d10beb 100644
--- a/Source/core/css/resolver/StyleResolverState.h
+++ b/Source/core/css/resolver/StyleResolverState.h
@@ -45,7 +45,8 @@ class StyleResolverState {
     STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(StyleResolverState);
 public:
-    StyleResolverState(Document&, Element*, RenderStyle* parentStyle = 0);
+    StyleResolverState(Document&, const ElementResolveContext&, PassRefPtr<RenderStyle>, PassRefPtr<RenderStyle> parentStyle);
+    StyleResolverState(Document&, Element*, PassRefPtr<RenderStyle>, RenderStyle* parentStyle = nullptr);

[rune, 2014/11/13 14:28:43]

How about making the parentStyle parameter mandatory non-null? It needs to be
non-null after construction regardlessly, and I think the logic for which parent
style to use in that case should be decided by the caller.

     ~StyleResolverState();
 
     // In FontFaceSet and CanvasRenderingContext2D, we don't have an element to grab the document from.
@@ -60,12 +61,6 @@ public:
 
     const ElementResolveContext& elementContext() const { return m_elementContext; }
 
-    void setStyle(PassRefPtr<RenderStyle> style)
-    {
-        m_style = style;
-        m_cssToLengthConversionData.setStyle(m_style.get());
-        m_fontBuilder.setStyle(m_style.get());
-    }
     const RenderStyle* style() const { return m_style.get(); }
     RenderStyle* style() { return m_style.get(); }
     PassRefPtr<RenderStyle> takeStyle() { return m_style.release(); }
@@ -76,7 +71,6 @@ public:
     const CSSAnimationUpdate* animationUpdate() { return m_animationUpdate.get(); }
     PassOwnPtrWillBeRawPtr<CSSAnimationUpdate> takeAnimationUpdate();
 
-    void setParentStyle(PassRefPtr<RenderStyle> parentStyle) { m_parentStyle = parentStyle; }
     const RenderStyle* parentStyle() const { return m_parentStyle.get(); }
     RenderStyle* parentStyle() { return m_parentStyle.get(); }