Performance: Tweaks to gutenberg_render_layout_support_flag

[spacedmonkey]

What?

Improve performance of gutenberg_render_layout_support_flag function, by moving variables to places where is it needed.

Why?

How?

Testing Instructions

Testing Instructions for Keyboard

Screenshots or screencast

[github-actions]

Flaky tests detected in cf10ed3.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/4159292716
📝 Reported issues:

• [Flaky Test] should close the inserter when clicking on the toggle button #48005 in /test/e2e/specs/editor/various/inserting-blocks.spec.js
• [Flaky Test] should forward delete across blocks #44353 in specs/editor/various/multi-block-selection.test.js
• [Flaky Test] shouldn't conflict with server-side autosave #35176 in specs/editor/various/autosave.test.js

[aristath]

Looks good to me!
The code makes sense, and it's a good practice to do this everywhere 👍

[hellofromtonya]

Hey @spacedmonkey is this fixing a bug or regression?

If no, then it's an enhancement, which is too late for 6.2.

[hellofromtonya]

In talking with Jonny, this is a code quality tweak for a performance enhancement. It's too late for it to go into 6.2. But it can backported to Core when 6.3 alpha opens (which will be next week).

[hellofromtonya]

https://core.trac.wordpress.org/ticket/57815 Trac ticket opened for this gutenberg-merge PR.

Removing the backport labels now that a Trac ticket is opened for its scope of work.