No bug - Remove a duplicate interface declaration in an IDL file. rs=me

--HG--
extra : rebase_source : 9f2a84a470e580841c5478e22f6ce9ae35ebc9d8

mailnews/base/public/nsIMsgFolder.idl

@@ -18,7 +18,6 @@ interface nsIMsgFilterList;
 interface nsIFile;
 interface nsIOutputStream;
 interface nsIInputStream;
-interface nsIFile;
 interface nsIMsgIdentity;
 interface nsIMsgThread;
 interface nsIMsgPluggableStore;