Merge StyleSheetCollection into ScopedStyleResolver.

sky/engine/core/dom/TreeScope.h

Index: sky/engine/core/dom/TreeScope.h
diff --git a/sky/engine/core/dom/TreeScope.h b/sky/engine/core/dom/TreeScope.h
index 4e2694a9d25c6bfa5783db04d25a1a6e4478a91b..3e9b28ca70d0695b83f43be1f49a329bd265927d 100644
--- a/sky/engine/core/dom/TreeScope.h
+++ b/sky/engine/core/dom/TreeScope.h
@@ -40,7 +40,6 @@ class Element;
 class HitTestResult;
 class Node;
 class ScopedStyleResolver;
-class StyleSheetCollection;
 
 // A class which inherits both Node and TreeScope must call clearRareData() in its destructor
 // so that the Node destructor no longer does problematic NodeList cache manipulation in
@@ -113,7 +112,6 @@ public:
     Element* getElementByAccessKey(const String& key) const;
 
     ScopedStyleResolver& scopedStyleResolver() const { return *m_scopedStyleResolver; }
-    StyleSheetCollection& styleSheets() const { return *m_styleSheets; }
 
 protected:
     TreeScope(ContainerNode&, Document&);
@@ -155,7 +153,6 @@ private:
     RawPtr<TreeScope> m_parentTreeScope;
 
     OwnPtr<ScopedStyleResolver> m_scopedStyleResolver;
-    OwnPtr<StyleSheetCollection> m_styleSheets;
 
     OwnPtr<DocumentOrderedMap> m_elementsById;
     OwnPtr<DocumentOrderedMap> m_imageMapsByName;