Stylesheets enqueued via `wp_enqueue_block_style` should only be enqueued when the block gets rendered

[aristath]

The issue was originally reported in ​https://make.wordpress.org/core/2021/12/15/using-multiple-stylesheets-per-block/#comment-42320 and a patch in Gutenberg exists in ​https://github.com/WordPress/gutenberg/pull/37848

In a block theme, styles for blocks only get printed when the block exists on a page. However, additional stylesheets enqueued via wp_enqueue_block_style always get printed.

More info and testing instructions can be found in the Gutenberg PR on ​https://github.com/WordPress/gutenberg/pull/37848

When using a block theme, make sure that additional block styles enqueued using wp_enqueue_block_style only get printed when the block exists on the page.

Trac ticket: https://core.trac.wordpress.org/ticket/54790

[Mamaduka]

I've tested this patch in the Gutenberg repo, and it works as expected - ​https://github.com/WordPress/gutenberg/pull/37848#pullrequestreview-849055787.

[aristath]

Thank you for testing and confirming the fix @Mamaduka!
The PR in Gutenberg was merged, so this is now a backport fix for 5.9 :)

[hellofromTonya]

As this is a backport from Gutenberg and was reported in RC1, moving into 5.9 for RC2 and marking for commit.

[hellofromTonya]

Self-assigning for trunk commit.

Committed via https://core.trac.wordpress.org/changeset/52556.

[hellofromTonya]

Whoopsie [52556] had the wrong ticket number :facepalm:. Manually adding it here.

In 52556:

Editor: Fix enqueueing additional styles in wp_enqueue_block_style() to print only when blocks render.

In a block theme, additional block styles registered using the wp_enqueue_block_style function should only get printed when the block exists on a page. However, they currently always get rendered.

This commit is a backport from Gutenberg that fixes the issue by printing the styles when a block renders.

Follow-up to [52069].

Props poena, aristath, Mamaduka.
Fixes #54787.

[hellofromTonya]

Re-opening for second committer review to backport to 5.9-branch for RC2.

[audrasjb]

I agree with the statement concerning anonymous functions, but let's commit this for now. It would be nice to adjust this in 6.0 though.

Marking as dev-reviewed.

[hellofromTonya]

Thanks @audrasjb. Prepping the backport commit now.

[hellofromTonya]

Consistent with the wrong ticket number :facepalm:

In 52559:

Editor: Fix enqueueing additional styles in wp_enqueue_block_style() to print only when blocks render.

In a block theme, additional block styles registered using the wp_enqueue_block_style function should only get printed when the block exists on a page. However, they currently always get rendered.

This commit is a backport from Gutenberg that fixes the issue by printing the styles when a block renders.

Follow-up to [52069].

Props poena, aristath, Mamaduka.
Merges [52556] to the 5.9 branch.
Fixes #54787.