What?

Fix a mismatch between the class added to some blocks and the styles added to the page.

Fixes #52195.

Why?

Because the styles engine is using an md5 of the block array, and adding keys to the array (like $block['is_inner_block]) changes the md5.

How?

Instead of adding a new key to $block, I used the same md5 technique to keep an array of root blocks.

Testing Instructions

Check that the md5-generated class works again:

• Add this markup to a post:

  <!-- wp:query {"queryId":1,"query":{"offset":0,"postType":"post","order":"desc","orderBy":"date","author":"","search":"","sticky":"","perPage":10}} -->
  <div class="wp-block-query">
    <!-- wp:post-template {"layout":{"type":"default"}} -->
    <!-- wp:post-title {"isLink":true,"style":{"elements":{"link":{"color":{"text":"var:preset|color|vivid-red"}}}}} /-->
    <!-- wp:post-excerpt /-->
    <!-- /wp:post-template -->
  </div>
  <!-- /wp:query -->

• Save the post
• Open the post in the frontend
• Check that color of the post title is red

Check that the Interactivity API server-side rendering still works fine:

• Open a post
• Add an HTML block
• Paste this code

  <div data-wp-context='{ "hide": false, "color": "red" }'>
    <div
      class="another"
      style="text-decoration: underline"
      data-wp-bind--hidden="context.hide"
      data-wp-class--show="!context.hide"
      data-wp-style--color="context.color"
      data-wp-text="context.color"
    >
      default value
    </div>
  </div>

• Take a look at the frontend, there should be a red underlined text saying "red" with the class "show"
• Change the "color" to "blue".
• Now there should be a blue underlined text saying "blue"
• Change "hide" to true.
• The text now should have a hidden attribute and the "show" class should not be there anymore