An creates a completely separate browsing context with its own window object, its own document, and most importantly;its own prototype chain. A function hooked on HTMLMediaElement.prototype in the parent window is not the same object as HTMLMediaElement.prototype in the iframe’s window. They’re entirely separate objects. If fermaw’s audio element lived inside an iframe, my prototype hook in the parent window would never fire.
Consider some of the more obscure tests that implementations must pass:
。关于这个话题，91视频提供了深入分析
（二）在铁路、城市轨道交通线路上放置障碍物，或者故意向列车投掷物品的；
Colors and finish