Import wpt@b73a0a32890ff293961eb55bb90ba57a5a711f48

https://github.com/web-platform-tests/wpt/compare/f8fb78a2c...b73a0a328

Using wpt-import in Chromium c314eaaf.
With Chromium commits locally applied on WPT:
  5fdbc88b "Convert all layer WPT tests to synchronous [...]
  256090d9 "Reland "Cross-origin support for [...]
  869e38fe "Add support for generating multiple canvas test [...]

Note to gardeners: This CL imports external tests and adds expectations
for those tests; if this CL is large and causes a few new failures,
please fix the failures by adding new lines to TestExpectations rather
than reverting. See:
https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md

Directory owners for changes in this CL:
hbos@chromium.org, hta@chromium.org, guidou@chromium.org, phancke@microsoft.com:
  external/wpt/webrtc

NOAUTOREVERT=true
R=rubber-stamper@appspot.gserviceaccount.com

No-Export: true
Validate-Test-Flakiness: skip
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Change-Id: I890c7ac1aa81b5f42f97c794815b6768ddd8adc1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5433033
Auto-Submit: WPT Autoroller <wpt-autoroller@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1283656}