Added Array.prototype.indexOf polyfill.

vendor/assets/javascripts/i18n.js

@@ -1,3 +1,40 @@
+// https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/indexOf
+if (!Array.prototype.indexOf) {
+  Array.prototype.indexOf = function(searchElement /*, fromIndex */) {
+    "use strict";
+
+    if (this === void 0 || this === null)
+      throw new TypeError();
+
+    var t = Object(this);
+    var len = t.length >>> 0;
+    if (len === 0)
+      return -1;
+
+    var n = 0;
+    if (arguments.length > 0) {
+      n = Number(arguments[1]);
+      if (n !== n) // shortcut for verifying if it's NaN
+        n = 0;
+      else if (n !== 0 && n !== (Infinity) && n !== -(Infinity))
+        n = (n > 0 || -1) * Math.floor(Math.abs(n));
+    }
+
+    if (n >= len)
+      return -1;
+
+    var k = n >= 0
+          ? n
+          : Math.max(len - Math.abs(n), 0);
+
+    for (; k < len; k++) {
+      if (k in t && t[k] === searchElement)
+        return k;
+    }
+    return -1;
+  };
+}
+
 // Instantiate the object
 var I18n = I18n || {};