Bug #000...trivial fix so no bug # filed. Fix a leak of nsIURI by using nsCOMPtr.

r=bienvenu.

mailnews/compose/src/nsMsgSend.cpp

@@ -1405,7 +1405,7 @@ PRUint32                  i;
           }
 
           nsXPIDLCString    spec;
-          nsIURI            *uri = doc->GetDocumentURL();
+          nsCOMPtr<nsIURI> uri = dont_AddRef(doc->GetDocumentURL());
 
           if (!uri)
             return NS_ERROR_OUT_OF_MEMORY;