Add encounteredError() to AssociatedInterfacePtrController.

mojo/public/js/lib/interface_endpoint_client.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 define("mojo/public/js/lib/interface_endpoint_client", [
   "console",
   "mojo/public/js/codec",
   "mojo/public/js/lib/control_message_handler",
   "mojo/public/js/lib/control_message_proxy",
   "mojo/public/js/lib/interface_endpoint_handle",
@@ skipping 214 matching lines @@
   };
 
   InterfaceEndpointClient.prototype.queryVersion = function() {
     return this.controlMessageProxy_.queryVersion();
   };
 
   InterfaceEndpointClient.prototype.requireVersion = function(version) {
     this.controlMessageProxy_.requireVersion(version);
   };
 
+  InterfaceEndpointClient.prototype.getEncounteredError = function() {
+    return this.encounteredError_;
+  };
+
   var exports = {};
   exports.InterfaceEndpointClient = InterfaceEndpointClient;
 
   return exports;
 });