externs: Make ReadableStream.getIterator typesafe
@@ -213,7 +213,7 @@ ReadableStream.prototype.cancel = function(reason) {};
/**
* @param {!ReadableStreamIteratorOptions=} options
- * @return {!AsyncIterator}
+ * @return {!AsyncIterator<VALUE>}
* @see https://streams.spec.whatwg.org/#rs-get-iterator
*/
ReadableStream.prototype.getIterator = function(options) {};
