Metal-ANGLE can ASSERT because MTL signal event code is compiled out
<rdar://problem/75132180>
Created attachment 422487 [details] Patch
Note that there are important steps to take when updating ANGLE. See https://trac.webkit.org/wiki/UpdatingANGLE
Comment on attachment 422487 [details] Patch Looks good. I vaguely remember this fix being done elsewhere (in the previous attempt to upstream the new Metal backend to ANGLE?) but sounds fine to get this fix in now. r+
Landed as part of r274547
Committed r274660 (235485@main): <https://commits.webkit.org/235485@main>