Drop handling for ms and O prefixes for CSS transition and animation events.

[realityking]

• Internet Explorer has never needed these prefixes (see https://caniuse.com/#feat=css-animation and https://caniuse.com/#feat=css-transitions)
• Opera 11.5 was the only release that needed a prefix (for CSS Transitions). Support for that version has already been removed in Remove Presto check (#11886) #11921

I think the Moz prefix could be dropped as well. It's only needed by Firefox 15 and older. This could open up a small refactor avoiding building these maps. WDYT?

[gaearon]

I don't feel comfortable dropping -ms- events without manual testing. Even caniuse is not guaranteed to be 100% accurate.

We’d need to test that all specific events in the list in this file either don't fire at all, or fire without a prefix, in every version after and including IE9.

[realityking]

That's fair. I took a slightly different approach to confirm it, I hope that works

First, Internet Explorer 9 is not an issue as it neither supports CSS Transitions nor CSS Animations.

Secondly, I created a file that contains the getVendorPrefixedEventName() code changed to be ES5 code and hosted it on GitHub pages (https://realityking.github.io/ie-css-event-test/).

Next I use the screenshot tool from Microsoft and BrowserStack to see what different IE put out for this code. You can see the result here https://developer.microsoft.com/en-us/microsoft-edge/tools/screenshots/?url=https%3A%2F%2Frealityking.github.io%2Fie-css-event-test%2F

Result: Both IE 10 and IE 11 use the unprefixed events.

[gaearon]

OK, this seems reasonable. Thanks.