[Feature]release train order

[roughsoft]

As we know，chromium is the mainstream browser(opera +edge+chrome)!
We can release some feature(for example:video,snapshotter,drag'n drop),these feature is very ready in chromium.
It must not be ready for all browser.

[roughsoft]

Not all web app must support all browser.

[roughsoft]

Some web app can support mainstream browser.

[shirshak55]

firefox is major browser tbh. And as ff follows webspec all webapp must support browser. I don't want to see another web skype that doesn't run on firefox.

[aslushnikov]

It must not be ready for all browser.

@roughsoft We have a high bar to release all API's across all browsers, and so far it worked out. We like this approach because a single API is easy for our clients to consume and maintain.