Improvement on error reporting of 'for await' loops

[adams85]

A minor fix related to async iterations (see #183 (comment))

[adams85]

Ooops, looks like this needs some more work:

af79159#diff-92a67081d35facbe8921de0638d8eccd7f7204c8b99a656abc3af2ea750857c1R3045-R3055

Please don't merge this yet.

[lahma]

even thought might not seem a good name, I think we should keep the naming that JS project has to make diffing and syncing easier

[adams85]

No problem, I'll revert it.

[adams85]

@lahma Ok, I went over it again, I think it's ready now.

Update: I squashed the corrections into the main commit to make it easier to review.

[lahma]

I think we should wait for the Esprima change first, it also renames the context.await to context.isAsync which is more logical and will also reflect here (unfortunately clashing). I'd like to also see how this changes reported errors against JS test suite after those changes (ideally this would show improvements 😉 )

[lahma]

Hey @adams85 I think we've forgotten this one, could you rebase? 🙂

[sebastienros]

Fixed the conflict from the GH UI, hopefully correctly.

[lahma]

I think it's all good, might need some styling adjustment later on but test cases are covering now 👍🏻