title: Error binding date input field with Polymer
body: <p>Just upgraded to Dart SDK version 1.10.0 on Windows 8 platform. Generated sample polymer app. Added following line to main_app.html:</p>
  
  <pre><code>&lt;input type="date" value="{{dob}}"/&gt;
  </code></pre>
  
  <p>and following line to main_app.dart:</p>
  
  <pre><code> @observable String dob = '';
  </code></pre>
  
  <p>Code generates following error:
  Failed to load resource: net::ERR_CACHE_MISS
  <a href="https://ssl.gstatic.com/chrome/components/doodle-notifier-01.html" rel="nofollow">https://ssl.gstatic.com/chrome/components/doodle-notifier-01.html</a>
  Observatory listening at <a href="http://127.0.0.1:50511/" rel="nofollow">http://127.0.0.1:50511/</a>
  </p>
  
  <p>Complete app is as follows:
  main_app.dart:</p>
  
  <pre><code>import 'dart:html';
  import 'package:paper_elements/paper_input.dart';
  import 'package:polymer/polymer.dart';
  /// A Polymer `&lt;main-app&gt;` element.
  @CustomTag('main-app')
  class MainApp extends PolymerElement {
    @observable String reversed = ''; 
  
    @observable String dob = '';   //added this line
  
    /// Constructor used to create instance of MainApp.
    MainApp.created() : super.created();
  
    void reverseText(Event event, Object object, PaperInput target) {
     reversed = target.value.split('').reversed.join('');
    }
  }
  </code></pre>
  
  <p>main_app.html</p>
  
  <pre><code>&lt;link rel="import" href="../../packages/polymer/polymer.html"&gt;
  &lt;link rel="import" href="../../packages/paper_elements/paper_input.html"&gt;
  &lt;polymer-element name="main-app"&gt;
    &lt;template&gt;
     &lt;style&gt;
      :host {
        display: block;
      }
     &lt;/style&gt;
     &lt;paper-input label="Type something..." on-keyup="{{reverseText}}"&gt;
     &lt;/paper-input&gt;
     &lt;p&gt;
         Reversed: {{ reversed }}
     &lt;/p&gt;
     &lt;input type="date" value="{{dob}}"/&gt; 
   &lt;/template&gt;
    &lt;script type="application/dart" src="main_app.dart"&gt;&lt;/script&gt;
  &lt;/polymer-element&gt;
  </code></pre>