Update Firefox support for mst.applyConstraints() (#17249)
Update Firefox support for mst.applyConstraints() (#17249)

This was implemented in Firefox 43:
https://bugzilla.mozilla.org/show_bug.cgi?id=912342

The same change is also made by mdn-bcd-collector:
https://github.com/mdn/browser-compat-data/pull/17224

This reverts what appears to be a mistaken edit while updating Chrome
which was probably intended to update the Opera data:
https://github.com/mdn/browser-compat-data/pull/1746

And now actually mirror the Opera data.

Part of https://github.com/mdn/browser-compat-data/pull/6526.
chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data