Fix a CHECK() in ByteStreamTeeEngine::Start() of a locked stream

Make sure we bail out if ReadableStream::AcquireDefaultReader() failed.

Fixed: 456617547
Bug: 427166012
Change-Id: Ibccc6bfc733e4617566eb00bb2b8d5c8901ae28a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7115848
Commit-Queue: Andrey Kosyakov <[email protected]>
Reviewed-by: Nate Chapin <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1540125}

Author: caseq

streams/readable-byte-streams/crashtests/tee-locked-stream.any.js

@@ -0,0 +1,9 @@
+// META: global=window,worker
+'use strict';
+
+test(() => {
+   const byteReadable = new ReadableStream({type: 'bytes'});
+   byteReadable.getReader();
+   assert_throws_js(TypeError, () => byteReadable.tee(), 'byteReadable.tee() must throw');
+}, 'tee() on a locked byte stream does not crash');
+