Remove function bind polyfill from worker.js

This is no longer required in Phantom.js 2.x

src/worker/worker.js

@@ -19,28 +19,6 @@
 
 self.window = {}; // to make UMD bundles work
 
-// Mozilla bind polyfill because phantomjs is stupid
-if (!Function.prototype.bind) {
-  Function.prototype.bind = function(oThis) {
-    if (typeof this !== "function") {
-      // closest thing possible to the ECMAScript 5 internal IsCallable function
-      throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
-    }
-
-    var aArgs = Array.prototype.slice.call(arguments, 1),
-        fToBind = this,
-        FNOP = function() {},
-        fBound = function() {
-          return fToBind.apply(this instanceof FNOP && oThis ? this : oThis, aArgs.concat(Array.prototype.slice.call(arguments)));
-        };
-
-    FNOP.prototype = this.prototype;
-    fBound.prototype = new FNOP();
-
-    return fBound;
-  };
-}
-
 importScripts('openpgp.js');
 var openpgp = window.openpgp;