This PR adds a new package syscall/js. Originally syscall/js is for
WebAssembly, but in GopherJS this package works as a wrapper of
github.com/gopherjs/gopherjs/js. With this package, developers can use
syscall/js both for GopherJS and WebAssembly.
The implementation is basically same as github.com/gohperjs/gopherwasm.
This PR adds a new package syscall/js. Originally syscall/js is for WebAssembly, but in GopherJS this package works as a wrapper of github.com/gopherjs/gopherjs/js. With this package, developers can use syscall/js both for GopherJS and WebAssembly.
The implementation is basically same as github.com/gohperjs/gopherwasm.
This is entirely the work of @hajimehoshi.