Summary:
Per https://caniuse.com/ and MDN,
* `-o-animation` superseded by unprefixed `animation` supported initially since Opera 12.1 released 11/2012, in later Opera versions with `-webkit-` prefix instead
* `@-o-keyframes` superseded by unprefixed `@keyframes` supported initially since Opera 12.1 released 11/2012, in later Opera versions with `-webkit-` prefix instead
* `-o-transform` superseded by unprefixed `transform` supported initially since Opera 12.1 released 11/2012
* `-o-transition` superseded by unprefixed `transition` supported initially since Opera 12.1 released 11/2012
Test Plan: None. Probably installing old browser versions if you don't trust documentation.
Reviewers: O1 Blessed Committers, valerio.bozzolan
Reviewed By: O1 Blessed Committers, valerio.bozzolan
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Differential Revision: https://we.phorge.it/D25916
22147cc03b