HTMLMediaElement events

[Grafikart]

The goal of this PR is to make this element act a bit like a HTMLMediaElement adding some methods, events and properties (this element will act a bit like a <video> element). An attribute must be set to add this feature since I don't want to introduce perf loss when events are not necessary (there is no use in loading the API for nothing).

I understand this feature add a bit of bloat so I submit it before adding the test (to avoid working on it further if you think it's not an interesting feature for the common use case).

ESlint & Test config

I tried using eslint with yarn run lint but I got errors about missing plugins. I don't want to add additional packages so I don't know if I'm missing something

The plugin "eslint-plugin-wc" was referenced from the config file in "package.json...

Another problem appears when I try to run test (dunno if it's my env or something I should set up before runing yarn run test)

The CHROME_PATH environment variable must be set to a Chrome/Chromium executable no older than Chrome stable

[justinribeiro]

Apologizes for delay in looking at this; let me put it through the paces and see about backfilling some of the tests.