Have StyleElement API take Document as a reference

Source/core/dom/StyleElement.h

Index: Source/core/dom/StyleElement.h
diff --git a/Source/core/dom/StyleElement.h b/Source/core/dom/StyleElement.h
index 38ffd156cb3a8174ba70d89350c06f2434ad7916..a26f5a52e10a632bb0969d7282f6637b932b5a9f 100644
--- a/Source/core/dom/StyleElement.h
+++ b/Source/core/dom/StyleElement.h
@@ -42,12 +42,12 @@ protected:
     CSSStyleSheet* sheet() const { return m_sheet.get(); }
 
     bool isLoading() const;
-    bool sheetLoaded(Document*);
-    void startLoadingDynamicSheet(Document*);
+    bool sheetLoaded(Document&);
+    void startLoadingDynamicSheet(Document&);
 
-    void processStyleSheet(Document*, Element*);
-    void removedFromDocument(Document*, Element*, ContainerNode* scopingNode = 0);
-    void clearDocumentData(Document*, Element*);
+    void processStyleSheet(Document&, Element*);
+    void removedFromDocument(Document&, Element*, ContainerNode* scopingNode = 0);
+    void clearDocumentData(Document&, Element*);
     void childrenChanged(Element*);
     void finishParsingChildren(Element*);