A transform stream that decodes bytes into strings.
See also:
https://nodejs.org/api/globals.html#class-textdecoderstream
https://nodejs.org/api/webstreams.html#class-textdecoderstream
new(?label:String, ?options:TextDecoderStreamOptions)
read onlyencoding:String
read onlyfatal:Bool
read onlyignoreBOM:Bool
read onlyreadable:ReadableStream
read onlywritable:WritableStream