prepareTemplateDom(template, elementName) {
    if (disableRuntime) {
      return;
    }
    const cssBuild = StyleUtil.getCssBuild(template);
    if (!nativeShadow && cssBuild !== 'shady' && !template._domPrepared) {
      template._domPrepared = true;
      StyleTransformer.domAddScope(template.content, elementName);
    }
  }
Prepare template for the given element type
@param {!HTMLTemplateElement} template
@param {string} elementName