<!DOCTYPE html>
<html>
<head>
<script src="bower_components/webcomponentsjs/webcomponents-lite.js">
</script>
<link rel="import" href="bower_components/polymer/polymer.html">
<title>Defining a Polymer Element from the Main Document</title>
</head>
<body>
<dom-module id="main-document-element">
<template>
<p>
Hi! I'm a Polymer element that was defined in the
main document!
</p>
</template>
<script>
HTMLImports.whenReady(function () {
Polymer({
is: 'main-document-element'
});
});
</script>
</dom-module>
<main-document-element></main-document-element>
</body>
</html>一些属性的说明：
https://www.polymer-project.org/1.0/docs/devguide/registering-elements#main-document-definitions
