Get rid of TreeBoundaryCrossingRules.

Source/core/dom/StyleEngine.h

Index: Source/core/dom/StyleEngine.h
diff --git a/Source/core/dom/StyleEngine.h b/Source/core/dom/StyleEngine.h
index ffe7ae975ae10cf81d7b82192fab07cd3e2455f7..644e266bcd62654ee98154a658288799db3d7652 100644
--- a/Source/core/dom/StyleEngine.h
+++ b/Source/core/dom/StyleEngine.h
@@ -121,6 +121,10 @@ public:
     bool usesRemUnits() const { return m_usesRemUnits; }
     void setUsesRemUnit(bool b) { m_usesRemUnits = b; }
 
+    bool hasTreeBoundaryCrossingRules() const { return m_treeBoundaryCrossingScopeCount; }
+    void addTreeBoundaryCrossingScope() { ++m_treeBoundaryCrossingScopeCount; }
+    void removeTreeBoundaryCrossingScope() { --m_treeBoundaryCrossingScopeCount; }
+
     void combineCSSFeatureFlags(const RuleFeatureSet&);
     void resetCSSFeatureFlags(const RuleFeatureSet&);
 
@@ -289,7 +293,7 @@ private:
     bool m_usesWindowInactiveSelector;
     bool m_usesRemUnits;
     unsigned m_maxDirectAdjacentSelectors;
-
+    unsigned m_treeBoundaryCrossingScopeCount;
     bool m_ignorePendingStylesheets;
     bool m_didCalculateResolver;
     OwnPtrWillBeMember<StyleResolver> m_resolver;