Merge the webio dep code in Blink

[ranjanan]

Currently WebIO uses Requires.jl to interface with Blink. However, we currently can't statically compile packages that use Requires.jl.

This helps support for shipping statically compiled Blink apps.

[ranjanan]

@pfitzseb or @MikeInnes could you please review? Thank you.

[pfitzseb]

This looks generally fine, but it might be better to use the code in WebIO#master and require WebIO@0.5 instead (that release will probably be out today).
Would you mind also preparing a PR to WebIO to remove the Blink integration over there?

---

If this is time critical we could also merge this as is and release a new Blink version before WebIO is updated though (but then you should add an upper bound on WebIO).

[pfitzseb]

JuliaLang/METADATA.jl#19479

[NHDaly]

Thanks for looking into this, Ranjan!

So I ran into this problem from here:
https://github.com/JuliaGizmos/WebIO.jl/blob/116956c4621c3cd18ff0689f8b86817d550dfa7b/src/WebIO.jl#L65-L80

Is that the same as what you're referring to?
Even after this PR, won't you still have the same problems with the other packages it @requires?

That said, I still think this PR is still beneficial! It seems weird to have Blink specifically logic conditionally defined in WebIO if we could just have it here instead.

[NHDaly]

EDIT: nvm apparently they need to be in the __init__ method. See next comment.

(Regarding the static compilation, i think the other part of the problem is that those lines are in the __init__ function. Is there any reason for that? Couldn't they be top-level statements? If they were, I think we could fix this problem by just making sure to import all those modules during the static compilation phase.

Maybe we should open a PR over there to move them out of __init__?)

[NHDaly]

JK please ignore the above:

https://github.com/MikeInnes/Requires.jl:

@require must be within the init method for your module. Here's an example that will create a new method of a function called myfunction only when both packages are present:

:(

[ranjanan]

Apologies for not getting to this sooner, but I have made the relevant PR on WebIO, so we could potentially merge this and JuliaGizmos/WebIO.jl#232 and tag new releases for both packages.

[twavv]

This was usurped by #201 and should be closed.