Refactoring: Extract DocumentInit for capture Document construction parameter.

Source/core/html/ImageDocument.h

Index: Source/core/html/ImageDocument.h
diff --git a/Source/core/html/ImageDocument.h b/Source/core/html/ImageDocument.h
index bdf4ee9919394bbb0caa08df2064facf4743bc02..95add872ab5dc26325213b60b29a5f5c140baf82 100644
--- a/Source/core/html/ImageDocument.h
+++ b/Source/core/html/ImageDocument.h
@@ -35,9 +35,9 @@ class HTMLImageElement;
 
 class ImageDocument FINAL : public HTMLDocument {
 public:
-    static PassRefPtr<ImageDocument> create(Frame* frame, const KURL& url)
+    static PassRefPtr<ImageDocument> create(const DocumentInitializer& initializer = DocumentInitializer())
     {
-        return adoptRef(new ImageDocument(frame, url));
+        return adoptRef(new ImageDocument(initializer));
     }
 
     CachedImage* cachedImage();
@@ -48,7 +48,7 @@ public:
     void imageClicked(int x, int y);
 
 private:
-    ImageDocument(Frame*, const KURL&);
+    ImageDocument(const DocumentInitializer&);
 
     virtual PassRefPtr<DocumentParser> createParser() OVERRIDE;
     virtual void dispose() OVERRIDE;