Add polyfill for .trim

src/polyfill.js

@@ -14,3 +14,9 @@ String.prototype.splitOnce = function (delimiter) {
     var components = this.split(delimiter);
     return [components.shift(), components.join(delimiter)];
 };
+
+if (!String.prototype.trim) {
+    String.prototype.trim = function () {
+        return this.replace(/^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g, '');
+    };
+}