[cjihrig]

This commit adds an internal util method that makes hidden values in the C++ layer visible in JS.

I'd like to use this to more easily access the hidden arrowMessage associated with syntax errors. Refs #3784, #3411, #2762

If you've already verified the type then simply use .As<TYPE>()

one comment, and if CI is happy then LGTM.

LGTM with the same comment as Trevor.

CI: https://ci.nodejs.org/job/node-test-pull-request/833/

UPDATE: CI looked like it had some unrelated issues. One more run, just to be sure: https://ci.nodejs.org/job/node-test-pull-request/836/

@cjihrig ... is this a candidate for LTS?

This PR alone is of little use in LTS. It only introduces a new internal method. It should be grouped in with #4013.

why is github showing zero commits and zero changes here? I believe that 5169311 on master comes from here but it's hard to be sure.

Oh interesting. That is very strange.

Seems to be a result of landing a commit and then force pushing this branch to close the PR. Probably shouldn't do that anymore.