Improve performance of wp_common_block_scripts_and_styles.

[spacedmonkey]

Trac ticket: https://core.trac.wordpress.org/ticket/58560

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[felixarntz]

This PR has a substantial performance benefit when using a block theme with theme support for wp-block-styles (see https://core.trac.wordpress.org/ticket/58560#comment:5), however there are some changes in here that I'd like other people's feedback on.

I think we should definitely move this forward, whether in time for WP 6.3, or alternatively for WP 6.4. I'll defer to other folks to decide that, depending on the feedback on the new themeStyle approach taken here.

[oandregal]

I've done some search, but it's difficult to pinpoint who was involved in this work, given all the moving code around between core and gutenberg. Playing by ear and pinging @aristath, as he has worked in this area, in case he can provide feedback.

[costdev]

Thanks for the PR @spacedmonkey! I left one nitpick that can be addressed here or in a follow-up "catch-all" commit, so it's not a blocker.

[spacedmonkey]

Thanks for the PR @spacedmonkey! I left one nitpick that can be addressed here or in a follow-up "catch-all" commit, so it's not a blocker.

@costdev Feedback complete.

[costdev]

Thanks for the update @spacedmonkey!

[audrasjb]

This looks good to ship @spacedmonkey 👍

[mukeshpanchal27]

Let one non-blocker nitpick for test other then look good to go.

[spacedmonkey]

Committed 30d6172