Convert XMLDocumentParser code to Use more reference

Source/core/dom/ScriptableDocumentParser.h

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 36 matching lines @@
     // These are used to expose the current line/column to the scripting system.
     virtual OrdinalNumber lineNumber() const = 0;
     virtual TextPosition textPosition() const = 0;
 
     void setWasCreatedByScript(bool wasCreatedByScript) { m_wasCreatedByScript = wasCreatedByScript; }
     bool wasCreatedByScript() const { return m_wasCreatedByScript; }
 
     ParserContentPolicy parserContentPolicy() { return m_parserContentPolicy; }
 
 protected:
-    explicit ScriptableDocumentParser(Document*, ParserContentPolicy = AllowScriptingContent);
+    explicit ScriptableDocumentParser(Document&, ParserContentPolicy = AllowScriptingContent);
 
 private:
     virtual ScriptableDocumentParser* asScriptableDocumentParser() OVERRIDE FINAL { return this; }
 
     // http://www.whatwg.org/specs/web-apps/current-work/#script-created-parser
     bool m_wasCreatedByScript;
     ParserContentPolicy m_parserContentPolicy;
 };
 
 }
 
 #endif // ScriptableDocumentParser_h