Improve RAII of StyleResolverState.

Source/core/css/resolver/StyleResolver.h

Index: Source/core/css/resolver/StyleResolver.h
diff --git a/Source/core/css/resolver/StyleResolver.h b/Source/core/css/resolver/StyleResolver.h
index 7470c15bf6e9599d1b85a5e009a06ae78072b174..72bb8ee05e9cb62d8af80bdc3673a0047f405ce5 100644
--- a/Source/core/css/resolver/StyleResolver.h
+++ b/Source/core/css/resolver/StyleResolver.h
@@ -55,6 +55,7 @@ class Interpolation;
 class MediaQueryEvaluator;
 class RuleData;
 class StyleKeyframe;
+class StyleBasisContext;
 class StylePropertySet;
 class StyleResolverStats;
 class StyleRule;
@@ -260,7 +261,10 @@ private:
     bool isFirstPage(int pageIndex) const;
     String pageName(int pageIndex) const;
 
-    bool pseudoStyleForElementInternal(Element&, const PseudoStyleRequest&, RenderStyle* parentStyle, StyleResolverState&);
+    PassRefPtr<RenderStyle> styleForContext(const StyleBasisContext&);
+    PassRefPtr<RenderStyle> parentStyleForContext(const StyleBasisContext&);
+
+    bool pseudoStyleForElementInternal(const PseudoStyleRequest&, StyleResolverState&, const StyleBasisContext&);
 
     Document& document() { return *m_document; }