Bug 1441019 - Remove duplicate namespace declaration. r=whimboo

MozReview-Commit-ID: CE1nnRainRE

--HG--
extra : rebase_source : 51cb3a625bed01b643801e007d97b89aaa82e713

testing/marionette/event.js

@@ -30,9 +30,6 @@ function getDOMWindowUtils(win) {
       .getInterface(Ci.nsIDOMWindowUtils);
 }
 
-/** @namespace */
-this.event = {};
-
 event.MouseEvents = {
   click: 0,
   dblclick: 1,