Untitled

//---------------------------------------------------------------------------------------//
// index.html
<!DOCTYPE html>

<html>
<head>
  <title>Test</title>
  <link rel="import" href="ext-table.html">
  <script src="packages/browser/dart.js"></script>
</head>

<body>
  <ext-table></ext-table>
  <script type="application/dart">export 'package:polymer/init.dart';</script>
</body>
</html>
//---------------------------------------------------------------------------------------//
// ext-table.html
<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="ext-td.html">

<polymer-element name="ext-table" noscript>
  <template>
    <p>test<p>
  </template>
</polymer-element>
//---------------------------------------------------------------------------------------//
//ext-td.html
<link rel="import" href="packages/polymer/polymer.html">
<polymer-element name="ext-td" extends="td">
   <template><content></content></template>
<script type="application/dart" src="ext-td.dart"></script>
</polymer-element>
//---------------------------------------------------------------------------------------//
//ext-td.dart
import 'package:polymer/polymer.dart';
import 'dart:html';

@CustomTag('ext-td')
class ExtTdElement extends TableCellElement with Polymer, Observable {

  ExtTdElement .created() : super.created() {
    polymerCreated();
  }
}