Have EditCommand classes deal with Document references, not pointers

Source/core/editing/UnlinkCommand.h

 /*
  * Copyright (C) 2006, 2008 Apple 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 14 matching lines @@
 
 #ifndef UnlinkCommand_h
 #define UnlinkCommand_h
 
 #include "core/editing/CompositeEditCommand.h"
 
 namespace WebCore {
 
 class UnlinkCommand : public CompositeEditCommand {
 public:
-    static PassRefPtr<UnlinkCommand> create(Document* document)
+    static PassRefPtr<UnlinkCommand> create(Document& document)
     {
         return adoptRef(new UnlinkCommand(document));
     }
 
 private:
-    explicit UnlinkCommand(Document*);
+    explicit UnlinkCommand(Document&);
 
     virtual void doApply();
     virtual EditAction editingAction() const { return EditActionUnlink; }
 };
 
 } // namespace WebCore
 
 #endif // UnlinkCommand_h