* Add dev command for building wasm backend
This aims to reduce the time spent building when testing with the wasm
backend. On my machine `yarn release` takes 20s while `yarn dev` takes
just 2s.
* Separate out building wasm
* add js interop testing
* checkout specific commit + fix bug in if stmt
* implement suggestions
* add to travis
* friendly error message + fix inverted if
* more intuitive order