fix imports link rel=stylesheet

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 804 matching lines @@
     }
     return receiverMirror.invoke(methodName, args).reflectee;
   }
 
   static MethodMirror _findMethod(ClassMirror type, Symbol name) {
     do {
       var member = type.declarations[name];
       if (member is MethodMirror) return member;
       type = type.superclass;
     } while (type != null);
+    return null; // unreachable
   }
 
   /**
    * Invokes a function asynchronously.
    * This will call `Platform.flush()` and then return a `new Timer`
    * with the provided [method] and [timeout].
    *
    * If you would prefer to run the callback using
    * [window.requestAnimationFrame], see the [async] method.
    */
@@ skipping 314 matching lines @@
     if (_sub != null) {
       if (_eventsLog.isLoggable(Level.FINE)) {
         _eventsLog.fine(
             'event.remove: [$_node].$_eventName => [$_model].$_path())');
       }
      _sub.cancel();
       _sub = null;
     }
   }
 }