Conditionally load WebComponents polyfill for use with Polymer, fire `WebComponentsReady` anyway

index.html

<script>
if ('registerElement' in document
 && 'createShadowRoot' in HTMLElement.prototype
 && 'import' in document.createElement('link')
 && 'content' in document.createElement('template')) {
  (function () {
    function ready() {
      setTimeout(function () {
        document.dispatchEvent(new CustomEvent('WebComponentsReady', {
          bubbles: true
        }));
      });
    }
    if (document.readyState === 'complete' || document.readyState === 'interactive') {
      ready();
    } else {
      window.addEventListener('DOMContentLoaded', ready);
    }
  })();
} else {
  document.write('<script src="bower_components\/webcomponentsjs\/webcomponents.min.js"><\/script>');
}
</script>