Also cache resolved CSS property names that are unprefixed

[vlakoff]

Coming from discussion #5516, in particular this message: #5516 (comment).

Excerpt:

However, I noticed that when querying a CSS property name that exists unprefixed, it doesn't get cached into the vendorProps map (contrarily to the prefixed names, that get cached).

Therefore, when querying unprefixed names, each time there is one lookup in the vendorProps map then one lookup in the emptyStyle object, whereas we could save the latter (after the cache is populated on first access).

Current code: finalPropName.js

Also, I just noticed that previously the unprefixed names were cached at well, but it is no longer the case since commit 2b5f5d5.

[timmywil]

Thanks for opening an issue. I don't know if it would actually make a noticeable difference in performance, but it does seem likely that the change in cache behavior was unintentional. We could also consider removing the cache altogether.

[timmywil]

We discussed this in the meeting. We're leaning towards removing the cache altogether on the main branch as it doesn't seem to add much value.

[mgol]

We went in a different direction and in #5583 we removed the cache altogether. See that PR for a more detailed discussion.