estFixtureExtension = {
    _fixtureTemplates: null,

    _elementsFixtured: false,

    get elementsFixtured () {
      return this._elementsFixtured;
    },

    get fixtureTemplates () {
      if (!this._fixtureTemplates) {
        // Copy fixtures to a true Array for Safari 7. This prevents their
        // `content` property from being improperly garbage collected.
        this._fixtureTemplates = Array.prototype.slice.apply(this.querySelectorAll('template'));
      }

      return this._fixtureTemplat