fixes #631 - better .bind() polyfill

@@ -44,12 +44,24 @@ if (!('phantom' in this)) {
 
 // Common polyfills
 if (typeof Function.prototype.bind !== "function") {
-    Function.prototype.bind = function(scope) {
+    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind#Compatibility
+    Function.prototype.bind = function (oThis) {
         "use strict";
-        var _function = this;
-        return function() {
-            return _function.apply(scope, arguments);
-        };
+        /* jshint -W055 */
+        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;
     };
 }