third_party/polymer/polymer/polymer-body.html

<polymer-element name="polymer-body" extends="body">

  <script>

  // upgrade polymer-body last so that it can contain other imported elements
  document.addEventListener('polymer-ready', function() {
    
    Polymer('polymer-body', Platform.mixin({

      created: function() {
        this.template = document.createElement('template');
        var body = wrap(document).body;
        var c$ = body.childNodes.array();
        for (var i=0, c; (c=c$[i]); i++) {
          if (c.localName !== 'script') {
            this.template.content.appendChild(c);
          }
        }
        // snarf up user defined model
        window.model = this;
      },

      parseDeclaration: function(elementElement) {
        this.lightFromTemplate(this.template);
      }

    }, window.model));

  });

  </script>

</polymer-element>