Fix some users of removed mirror API.

pkg/polymer/lib/src/instance.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of polymer;
 
 /**
  * Use this annotation to publish a field as an attribute. For example:
  *
  *     class MyPlaybackElement extends PolymerElement {
@@ skipping 776 matching lines @@
   /** Call [methodName] method on this object with [args]. */
   invokeMethod(Symbol methodName, List args) =>
       _invokeMethod(this, methodName, args);
 
   /** Call [methodName] method on [receiver] with [args]. */
   static _invokeMethod(receiver, Symbol methodName, List args) {
     // TODO(sigmund): consider making callbacks list all arguments
     // explicitly. Unless VM mirrors are optimized first, this will be expensive
     // once custom elements extend directly from Element (see issue 11108).
     var receiverMirror = reflect(receiver);
-    var method = receiverMirror.type.methods[methodName];
-    if (method != null) {
+    var method = receiverMirror.type.declarations[methodName];
+    if (method != null && method is MethodMirror) {
       // This will either truncate the argument list or extend it with extra
       // null arguments, so it will match the signature.
       // TODO(sigmund): consider accepting optional arguments when we can tell
       // them appart from named arguments (see http://dartbug.com/11334)
       args.length = method.parameters.where((p) => !p.isOptional).length;
     }
     return receiverMirror.invoke(methodName, args).reflectee;
   }
 
   /**
@@ skipping 264 matching lines @@
 
 class _PropertyValue {
   Object oldValue, newValue;
   _PropertyValue(this.oldValue);
 }
 
 class _PolymerExpressionsWithEventDelegate extends PolymerExpressions {
   prepareBinding(String path, name, node) =>
       Polymer.prepareBinding(path, name, node, super.prepareBinding);
 }