Function isFromEmbed

src/utils/log.js:625–627

* @param {!Window} win * @param {!Element=} opt_element * @return {boolean} isEmbed

(win, opt_element)

 * @return {boolean} isEmbed
 */
function isFromEmbed(win, opt_element) {
  return opt_element && opt_element.ownerDocument.defaultView != win;
}

/**
 * Throws an error if the first argument isn't trueish.