Generalize descriptor processing to remove hardcoding in process-css-properties.py. No longer need to explicitly add @font-face, etc. to the script, just to the json file.
<rdar://problem/103605497>
Pull request: https://github.com/WebKit/WebKit/pull/7966
Committed 258345@main (9d2d5fe065c1): <https://commits.webkit.org/258345@main> Reviewed commits have been landed. Closing PR #7966 and removing active labels.