Properly escape CSS identifiers in serialization.
Note that this also affects the IDL accessors (e.g. name()),
but this is in line with Safari and Firefox.
Fixed: 343000522
Change-Id: I7ac93421aa7b550f9f6f0192899fab1ae82aba30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5604769
Auto-Submit: Steinar H Gunderson sesse@chromium.org
Commit-Queue: Rune Lillesveen futhark@chromium.org
Reviewed-by: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1315147}