Remove unneeded nsChangeHint include. Bug 254790, r+sr=dbaron

content/base/public/nsIDocument.h

@@ -40,7 +40,6 @@
 #include "nsISupports.h"
 #include "nsEvent.h"
 #include "nsString.h"
-#include "nsChangeHint.h"
 #include "nsCOMArray.h"
 #include "nsIDocumentObserver.h"
 #include "nsCOMPtr.h"

content/base/public/nsIDocumentObserver.h

@@ -38,7 +38,6 @@
 #define nsIDocumentObserver_h___
 
 #include "nsISupports.h"
-#include "nsChangeHint.h"
 
 class nsIAtom;
 class nsIContent;