No bug - Fix Vim modeline in PluginModuleChild.cpp. rs=khuey DONTBUILD

--HG--
extra : rebase_source : ec84b4b231784a111375092339b4b0404570fb47

dom/plugins/ipc/PluginModuleChild.cpp

@@ -1,5 +1,5 @@
 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
-/* vim: sw=4 ts=4 et : */
+/* vim: set sw=4 ts=4 et : */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *