Method cancel

examples/io/streams/modules/streams.js:278–283

(reason)

		return IsReadableStreamLocked(stream);
	}
	cancel(reason) {
		const stream = ReadableStreamBrand.get(this);
		if (IsReadableStreamLocked(stream))
			return Promise.reject(new TypeError("stream locked"));
		return ReadableStreamCancel(stream, reason);
	}
	getReader(options) {
		const stream = ReadableStreamBrand.get(this);
		if (!options || !("mode" in options) || (options.mode === undefined))