Don't pre-package libs into browser version

[RubenVerborgh]

Instead of 3eb6b2d, we can also do https://github.com/defunctzombie/package-browser-field-spec#replace-specific-files---advanced

[RubenVerborgh]

@rubensworks This did not work; I assume because @trust/webcrypto is a transitive dependency.

[rubensworks]

Hmm, that's too bad.

Perhaps it can be solved by either:

• Add a browser entry to @trust/webcrypto directly. (This assume we have push-access or can PR to https://github.com/anvilresearch/webcrypto)
• Or, we can create an isomorphic-webcrypto wrapper package, similar to isomorphic-fetch.

[RubenVerborgh]

@rubensworks Very probably; however, we don't want to touch the @trust libraries for now. (They seem to have an issue on this though: anvilresearch/webcrypto#57) Maybe I can have a look at getting rid of them altogether in favor of https://www.npmjs.com/package/isomorphic-webcrypto.

[RubenVerborgh]

…which turns out to be just https://github.com/kevlened/isomorphic-webcrypto/blob/master/src/index.js

[rubensworks]

Oh, so that's exactly what we need then :-)

isomorphic-webcrypto seems up-to-date with @trust/webcrypto, so it should be low-effort to transition to that.