Removing null code. No bug number. r=nisheeth

git-svn-id: svn://10.0.0.236/trunk@52479 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/layout/forms/nsHTMLButtonControlFrame.cpp

@@ -104,7 +104,8 @@ nsrefcnt nsHTMLButtonControlFrame::Release(void)
   return 1;
 }
 
-nsresult
+// Frames are not refcounted, no need to AddRef
+NS_IMETHODIMP
 nsHTMLButtonControlFrame::QueryInterface(const nsIID& aIID, void** aInstancePtr)
 {
   NS_PRECONDITION(0 != aInstancePtr, "null ptr");