Previously, -scheduler=none wasn't possible for WASM targets:
$ tinygo run -target=wasm -scheduler=none ./testdata/stdlib.go
src/runtime/runtime_wasm_js.go:34:2: attempted to start a goroutine without a scheduler
With this commit, it works just fine:
$ tinygo run -target=wasm -scheduler=none ./testdata/stdlib.go
stdin: /dev/stdin
stdout: /dev/stdout
stderr: /dev/stderr
pseudorandom number: 1298498081
strings.IndexByte: 2
strings.Replace: An-example-string
Supporting `-scheduler=none` has some benefits:
* it reduces file size a lot compared to having a scheduler
* it allows JavaScript to call exported functions
