Palemoon 28.5 compatibility

This is a patch for compatibility with PM 28.5 based on Billylll@'s
patch posted to madand#7.

common/content/dactyl.js

@@ -1932,7 +1932,7 @@ var Dactyl = Module("dactyl", XPCOM(Ci.nsISupportsWeakReference, ModuleBase), {
         dactyl.log(_("dactyl.modulesLoaded"), 3);
 
         userContext.DOM = Class("DOM", DOM, {
-            init(sel, ctxt) {
+            init: function init(sel, ctxt) {
                 return DOM(sel, ctxt || buffer.focusedFrame.document);
             }
         });

common/content/mow.js

@@ -7,7 +7,7 @@
 "use strict";
 
 var MOW = Module("mow", {
-    init() {
+    init: function init() {
         let proxy = new Proxy(this, {
             get(target, prop, receiver) {
                 if (prop in target)