Carry the project to completion

In [internals](https://internals.rust-lang.org/t/need-help-with-emscripten-port/3154/143) you menchend that this neads work to push it to completion. Can we make a checklist or separate issues defining what still needs to be done?

Start with the linked internals discussion about the Emscripten port and determine which completion tasks are still outstanding. The issue is done when the remaining work is captured as a concrete checklist or as separate, actionable issues.

Written by the indexing model from the issue text.