rhodecode.js: implement array.filter for backward compatibility

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter#Compatibility
under MIT license / public domain
https://developer.mozilla.org/en-US/docs/MDN/About#Copyrights_and_licenses

rhodecode/public/js/rhodecode.js

@@ -70,6 +70,45 if(!Array.prototype.indexOf) {
     };
 }
 
+/* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter#Compatibility
+   under MIT license / public domain, see
+   https://developer.mozilla.org/en-US/docs/MDN/About#Copyrights_and_licenses */
+if (!Array.prototype.filter)
+{
+    Array.prototype.filter = function(fun /*, thisArg */)
+    {
+        "use strict";
+
+        if (this === void 0 || this === null)
+            throw new TypeError();
+
+        var t = Object(this);
+        var len = t.length >>> 0;
+        if (typeof fun !== "function")
+            throw new TypeError();
+
+        var res = [];
+        var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
+        for (var i = 0; i < len; i++)
+        {
+            if (i in t)
+            {
+                var val = t[i];
+
+                // NOTE: Technically this should Object.defineProperty at
+                //       the next index, as push can be affected by
+                //       properties on Object.prototype and Array.prototype.
+                //       But that method's new, and collisions should be
+                //       rare, so use the more-compatible alternative.
+                if (fun.call(thisArg, val, i, t))
+                    res.push(val);
+            }
+        }
+
+        return res;
+    };
+}
+
 /**
  * A customized version of PyRoutes.JS from https://pypi.python.org/pypi/pyroutes.js/
  * which is copyright Stephane Klein and was made available under the BSD License.