Bug 1615399. Stop using NS_ERROR_DOM_TYPE_ERR in BodyStream. r=baku

Differential Revision: https://phabricator.services.mozilla.com/D62790

--HG--
extra : moz-landing-system : lando

dom/base/BodyStream.cpp

@@ -336,10 +336,16 @@ void BodyStream::ErrorPropagation(JSContext* aCx,
   }
 
   // Let's use a generic error.
-  RefPtr<DOMException> error = DOMException::Create(NS_ERROR_DOM_TYPE_ERR);
+  ErrorResult rv;
+  // XXXbz can we come up with a better error message here to tell the
+  // consumer what went wrong?
+  rv.ThrowTypeError(u"Error in body stream");
 
   JS::Rooted<JS::Value> errorValue(aCx);
-  if (ToJSValue(aCx, error, &errorValue)) {
+  bool ok = ToJSValue(aCx, std::move(rv), &errorValue);
+  MOZ_RELEASE_ASSERT(ok, "ToJSValue never fails for ErrorResult");
+
+  {
     MutexAutoUnlock unlock(mMutex);
     JS::ReadableStreamError(aCx, aStream, errorValue);
   }

testing/web-platform/tests/service-workers/service-worker/fetch-event-respond-with-response-body-with-invalid-chunk.https.html

@@ -11,15 +11,21 @@ const WORKER =
   'resources/fetch-event-respond-with-response-body-with-invalid-chunk-worker.js';
 const SCOPE =
   'resources/fetch-event-respond-with-response-body-with-invalid-chunk-iframe.html';
-// Called by the iframe when done.
-var done;
-var done_was_called = new Promise(resolve => done = resolve);
+
+// Called by the iframe when it has the reader promise we should watch.
+var set_reader_promise;
+let reader_promise = new Promise(resolve => set_reader_promise = resolve);
+
+var set_fetch_promise;
+let fetch_promise = new Promise(resolve => set_fetch_promise = resolve);
 
 // This test creates an controlled iframe that makes a fetch request. The
 // service worker returns a response with a body stream containing an invalid
 // chunk.
-promise_test(t => {
-    return service_worker_unregister_and_register(t, WORKER, SCOPE)
+promise_test(async t => {
+    // Start off the process.
+    let errorConstructor;
+    await service_worker_unregister_and_register(t, WORKER, SCOPE)
       .then(reg => {
            add_completion_callback(() => reg.unregister());
            return wait_for_state(t, reg.installing, 'activated');
@@ -27,8 +33,14 @@ promise_test(t => {
       .then(() => with_iframe(SCOPE))
       .then(frame => {
           t.add_cleanup(() => frame.remove())
-        })
-      .then(() => done_was_called)
-      .then(result => assert_equals(result, 'PASS'));
+          errorConstructor = frame.contentWindow.TypeError;
+        });
+
+    await promise_rejects_js(t, errorConstructor, reader_promise,
+                             "read() should be rejected");
+    // Fetch should complete properly, because the reader error is caught in
+    // the subframe.  That is, there should be no errors _other_ than the
+    // reader!
+    return fetch_promise;
   }, 'Response with a ReadableStream having non-Uint8Array chunks should be transferred as errored');
 </script>

testing/web-platform/tests/service-workers/service-worker/resources/fetch-event-respond-with-response-body-with-invalid-chunk-iframe.html

@@ -5,10 +5,11 @@
 <script>
 'use strict';
 
-fetch('body-stream-with-invalid-chunk').then(resp => {
+parent.set_fetch_promise(fetch('body-stream-with-invalid-chunk').then(resp => {
     const reader = resp.body.getReader();
-    return reader.read().then(
-      () => parent.done('FAIL: read() should be rejected'),
-      () => parent.done('PASS'));
-  }).catch(e => parent.done('FAIL: ' + e));
+    const reader_promise = reader.read();
+    parent.set_reader_promise(reader_promise);
+    // Suppress our expected error.
+    return reader_promise.catch(() => {});
+  }));
 </script>