Issue 3225 - Make sure Policy.shouldAllow can be overwritten by Diagnostics extension

lib/contentPolicy.js

Index: lib/contentPolicy.js
===================================================================
--- a/lib/contentPolicy.js
+++ b/lib/contentPolicy.js
@@ -66,17 +66,17 @@ var Policy = exports.Policy =
    * Called on module startup, initializes various exported properties.
    */
   init: function()
   {
     // whitelisted URL schemes
     for (let scheme of Prefs.whitelistschemes.toLowerCase().split(" "))
       this.whitelistSchemes.add(scheme);
 
-    Utils.addChildMessageListener("AdblockPlus:ShouldAllow", this.shouldAllow.bind(this));
+    Utils.addChildMessageListener("AdblockPlus:ShouldAllow", message => this.shouldAllow(message));
 
     // Generate class identifier used to collapse nodes and register
     // corresponding stylesheet.
     let collapsedClass = "";
     let offset = "a".charCodeAt(0);
     for (let i = 0; i < 20; i++)
       collapsedClass +=  String.fromCharCode(offset + Math.random() * 26);
     Utils.addChildMessageListener("AdblockPlus:GetCollapsedClass", () => collapsedClass);