events: expose Event statics

[benjamingr]

Expose Event statics (Event.NONE etc). See Event phase constants.

• Chrome, Firefox, Edge, and Safari implement these.
• IE11 implements all of these except NONE (for some reason).

I think these are required on the event interface (as constants).

They are as-enumerable as they are in browsers though I did not add a specific test for enumerability (I can if people feel strongly about it)

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[benjamingr]

Also I did not fix the tests at the top that check eventPhase with the numeric values (rather than constants) to not create coupling, but I can happily change that.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/31644/

[jasnell]

Adding a comment in here that we currently do not use the CAPTURING_PHASE and BUBBLING_PHASE but that they need to be preserved anyway because of the spec would be good.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/31911/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/32009/

[jasnell]

Adding a fixup commit resolving the rebase conflict.

[jasnell]

@benjamingr ... can I ask to you squash the commits here?

[benjamingr]

Sure though I have a computer without built node so I am doing everything "blind" until early next week.

[benjamingr]

@jasnell I see there is a merge commit present - I assume that's not intentional? Can I pluck it out and squash the other two?

[jasnell]

Actually, don't worry about squashing or fixing up. I'm combining all these PRs into a single PR to make landing them easier

[benjamingr]

@jasnell to be explicit, you have my explicit consent (and blessing) to do as you wish with the code here and in the other PRs (and in follow up event-target PRs when I get back to my workstation next week).

[jasnell]

Closing in favor of #34015 (which combines this and other eventtarget PRs into a single to make landing easier