Simplify tree scope tracking in StyleEngine.

sky/engine/core/dom/StyleSheetCollection.h

Index: sky/engine/core/dom/StyleSheetCollection.h
diff --git a/sky/engine/core/dom/StyleSheetCollection.h b/sky/engine/core/dom/StyleSheetCollection.h
index 48d2377db2004cef7770eaf8085fdf607db03ade..bdd208f286c1071a89050d23c969308e9c7aaf73 100644
--- a/sky/engine/core/dom/StyleSheetCollection.h
+++ b/sky/engine/core/dom/StyleSheetCollection.h
@@ -38,6 +38,7 @@ namespace blink {
 
 class CSSStyleSheet;
 class ContainerNode;
+class HTMLStyleElement;
 class StyleEngine;
 class TreeScope;
 
@@ -54,9 +55,8 @@ public:
     Vector<RefPtr<CSSStyleSheet> >& activeAuthorStyleSheets() { return m_activeAuthorStyleSheets; }
     const Vector<RefPtr<CSSStyleSheet> >& activeAuthorStyleSheets() const { return m_activeAuthorStyleSheets; }
 
-    void addStyleSheetCandidateNode(Node*, bool createdByParser);
-    void removeStyleSheetCandidateNode(Node*, ContainerNode* scopingNode);
-    bool hasStyleSheetCandidateNodes() const { return !m_styleSheetCandidateNodes.isEmpty(); }
+    void addStyleSheetCandidateNode(HTMLStyleElement&);
+    void removeStyleSheetCandidateNode(HTMLStyleElement&);
 
     void updateActiveStyleSheets(StyleEngine*);