fix(protractor): add dummy isPending function

See #1021

Author: hankduan

lib/protractor.js

@@ -748,6 +748,17 @@ var buildElementHelper = function(ptor) {
     }
   };
 
+  /**
+   * Webdriver rely on this function to be present on Promises, so adding
+   * this dummy function as we inherited from webdriver.promise.Promise, but
+   * this function is irrelevant to our usage
+   *
+   * @return {boolean} Always false as ElementFinder is never in pending state.
+   */
+  ElementFinder.prototype.isPending = function() {
+    return false;
+  };
+
   var element = function(locator) {
     return new ElementFinder(locator);
   };