include runtime dependencies for emmet

[marcdumais-work]

Fixes #18

As suggested here, I added one step to install the production dependencies for emmet: #18 (comment)

It seems to fix #18 and as well make the emmet built-in work: see second video here: #18 (comment)

How to test

Build this branch using yarn, then test the emmet built-in as per the following comment, and verify that this scenario no longer generates an exception: #18 (comment)

[vince-fugnitto]

@marcdumais-work would it be harmful to do the same thing for all extensions as to not have any potential runtime dependencies issues?

[vince-fugnitto]

I'm fine as well with doing the update on a case-per-case basis as well if that's the strategy.

[akosyakov]

@vince-fugnitto we could check whether package.json has dependencies field and only then run the script

[vince-fugnitto]

@marcdumais-work I verified the changes and I now see emmet snippets being successfully contributed and suggested when editing html files. I also no longer see the frontend error reported.

[marcdumais-work]

would it be harmful to do the same thing for all extensions as to not have any potential runtime dependencies issues?

I do not think it would be harmful, and Anton's suggestion of narrowing it down to extensions that have runtime dependencies could be even better. However I am hesitant to do this right now since I do not have much time to properly test all affected built-ins.

I've opened an issue instead for now: #23

[marcdumais-work]

@akosyakov are you fine with me merging this PR?

[akosyakov]

fine :)