Support Skip-Ad media session action

[jiajiabingcheng]

• Specification title: Support Skip-Ad media session action

• Specification or proposal URL (if available): https://www.w3.org/TR/mediasession/#dom-mediasessionaction-skipad https://github.com/w3c/mediasession/pull/203#issuecomment-432529816

• Explainer URL (if available): https://developer.chrome.com/blog/media-updates-in-chrome-73#skipad

• Proposal author(s) (@-mention GitHub accounts): @jiajiabingcheng

• Caniuse.com URL (optional):

• Bugzilla URL (optional):

• Mozillians who can provide input (optional):

• WebKit standards-position: https://github.com/WebKit/standards-positions/issues/350

[zcorpan]

cc @alastor0325 @padenot

[jyasskin]

https://caniuse.com/?search=skipad says this shipped in Firefox 82.

[saschanaz]

Seems right: https://bugzilla.mozilla.org/show_bug.cgi?id=1582569