Repro case for Polymer 1.0 element which can't be instantiated in Shady DOM

gistfile1.txt

<!--
Repro case for bug that appears under Shady DOM.

Attempting to instantiate this component will trigger an exception. Both the
hostAttributes and the property change observer appear necessary to trigger the
exception.
-->

<link rel="import" href="../bower_components/polymer/polymer.html">

<script>
Polymer({

  hostAttributes: {
    target: 'foo'
  },

  is: 'repro-element',

  properties: {
    target: {
      value: null,
      observer: 'targetChanged'
    }
  },

  targetChanged: function(value) {
    console.log("target: " + value);
  }

});
</script>