A browser-compatible implementation of WritableStream.
WritableStream
See also:
https://nodejs.org/api/globals.html#class-writablestream
https://nodejs.org/api/webstreams.html#class-writablestream
new(?underlyingSink:WritableStreamUnderlyingSink, ?strategy:QueuingStrategy)
read onlylocked:Bool
abort(?reason:Any):Promise<Void>
close():Promise<Void>
getWriter():WritableStreamDefaultWriter