Add boolean matches(String selectors) method

[Greunlis]

I propose adding a matches method as defined here: https://developer.mozilla.org/en-US/docs/Web/API/Element/matches

[niloc132]

Thanks for the submission - at the very least, we would want to have tests to accompany it. I would also be concerned about a caller who cannot tell if "false" means "doesn't match" or "matches, but the method doesn't exist".

Note however that this is already supported in elemental2.dom.Element, as well as many other other methods not found in dom.client.Element and subclasses. As Elemental2 is auto generated (from hand maintained externs) it will tend to be more up to date with what the rest of the browser world can support.

Does it make sense to just use elemental2 for your use cases where modern APIs are required?

[Greunlis]

Thanks for pointing me to elemental2! Adding it just for this method alone seems like an overkill, but I might find other use cases in our codebase, I'll give it some more thought and either add a test or close this pull request as unnecessary.