Bug 1444940 [wpt PR 9926] - Streams: Modify tests to expect abort reason passthrough...

Bug 1444940 [wpt PR 9926] - Streams: Modify tests to expect abort reason passthrough, a=testonly

Automatic update from web-platform-testsStreams: Modify tests to expect abort reason passthrough (#9926)

This tests the changes in https://github.com/whatwg/streams/pull/903.

Replace expectations that a TypeError will be stored after abort() is
called with with expectations that the reason passed to abort() will be
stored instead.

Also add a test of the stored error on the readable side of a
TransformStream after abort() has been called on the writable size. This
was not explicitly tested.

Also fix a bug in the general.js test: it didn't wrap a call to
assert_unreached properly, so a failure would have shown up as an
unhandled rejection rather than being reported properly.

wpt-commits: 81468a0b88d771af9dfa0feb5de99367e32d4b6e
wpt-pr: 9926
wpt-commits: 81468a0b88d771af9dfa0feb5de99367e32d4b6e
wpt-pr: 9926