Fixes names collisions in content.js

extensions/firefox/chrome/content.js

@@ -20,6 +20,9 @@
 
 'use strict';
 
+(function contentScriptClosure() {
+  // we need to use closure here -- we are running in the global context
+
   const Cc = Components.classes;
   const Ci = Components.interfaces;
   const Cm = Components.manager;
@@ -33,7 +36,8 @@ var isRemote = Services.appinfo.processType ===
     Services.appinfo.PROCESS_TYPE_CONTENT;
 
 // Factory that registers/unregisters a constructor as a component.
-function Factory() {}
+  function Factory() {
+  }
 
   Factory.prototype = {
     QueryInterface: XPCOMUtils.generateQI([Ci.nsIFactory]),
@@ -96,3 +100,4 @@ if (isRemote) {
       shutdown();
     });
   }
+})();