Resync web-platform-tests/webmessaging from upstream.
Created attachment 403876 [details] Patch
This patch modifies the imported WPT tests. Please ensure that any changes on the tests (not coming from a WPT import) are exported to WPT. Please see https://trac.webkit.org/wiki/WPTExportProcess
Comment on attachment 403876 [details] Patch rs=me
Committed r264181: <https://trac.webkit.org/changeset/264181> All reviewed patches have been landed. Closing bug and clearing flags on attachment 403876 [details].
<rdar://problem/65280884>