Mapping the promise returned from the helpers to the executor's resolve, and reject
methods. We also need to catch the error in the promise chain that's
created inside exitFullscreenHelper_.
Fixes#7298.
iPhone's native fullscreen isn't always desirable as you can't overlay controls or anything else. Adds an option to prefer "full window" mode over the video el's fullscreen.
If the preferFullWindow option is set to true, on a browser that does not support the proper fullscreen API but does support fullscreen on the video element (i.e. iPhone), then requestFullscreenHelper_() should call enterFullWindow() instead of fullscreen on the tech.
On browsers that implement the Unprefixed Fullscreen API, pass a FullscreenOptions dictionary to requestFullscreen.
Add `fullscreenOptions` option with default value of `{navigationUI: 'hide'}` to player.
See https://fullscreen.spec.whatwg.org/#dictdef-fullscreenoptions
