Currently, FetchStreamReader never signals to the JS stream code that
the reader has been closed. This means that when a ServiceWorker
passes a ReadableStream to respondWith and the HTTP Channel gets
canceled, the JS code will keep generating the stream without ever
realizing the data's not going anywhere. It's necessary to cancel
the reader. Or do something like that, this seems to work!
Currently, FetchStreamReader never signals to the JS stream code that
the reader has been closed. This means that when a ServiceWorker
passes a ReadableStream to respondWith and the HTTP Channel gets
canceled, the JS code will keep generating the stream without ever
realizing the data's not going anywhere. It's necessary to cancel
the reader. Or do something like that, this seems to work!