Block Editor: Revert anchor support for dynamic blocks

[Mamaduka]

The featured introduced content markup regression in WP 6.2, and it's too complex to resolve in this cycle. So instead, we're going to remove the feature from the release.

Note: We're not reverting changes made to the $attributes_to_merge list. It is necessary to continue work on the feature in the Gutenberg plugin.

Original commit: https://core.trac.wordpress.org/changeset/55230
Related Gutenberg PR: ​https://github.com/WordPress/gutenberg/pull/48592

Testing Instructions

Use the instructions provided in the bug report - ​https://github.com/WordPress/gutenberg/issues/48232#issue-1590604475.

Trac ticket: https://core.trac.wordpress.org/ticket/57830

[hellofromTonya]

Self-assigning for revert commit.

Note: We're not reverting changes made to the $attributes_to_merge list. It is necessary to continue work on the feature in the Gutenberg plugin.

So this is a partial revert of https://core.trac.wordpress.org/changeset/55230.

@hellofromtonya, correct. Only removing ABSPATH . WPINC . '/block-supports/anchor.php' file, but keeping the $attributes_to_merge change, so we can continue work in the plugin.

[hellofromTonya]

Testing Instructions

Steps to Reproduce

• Step 1: Create a new post.
• Step 2: Switch to the Code Editor.
• Step 3: Insert the following markup into the editor:

  <!-- wp:paragraph -->
  <p>Paragraph without anchor</p>
  <!-- /wp:paragraph -->
  
  <!-- wp:paragraph -->
  <p id="anchor">Paragraph with anchor</p>
  <!-- /wp:paragraph -->
  
  <!-- wp:heading -->
  <h2>Heading without anchor</h2>
  <!-- /wp:heading -->
  
  <!-- wp:heading -->
  <h2 id="anchor">Heading with anchor</h2>
  <!-- /wp:heading -->
  
  <!-- wp:group {"layout":{"type":"constrained"}} -->
  <div id="anchor" class="wp-block-group"></div>
  <!-- /wp:group -->
  

• Step 4: Publish (or update) the post. 🐞 The markup is changed.

Expected Results:

When testing a patch to validate it works as expected:

• ✅ The markup should not change.

When reproducing the bug:

• The markup is changed to:

  <!-- wp:paragraph -->
  <p>Paragraph without anchor</p>
  <!-- /wp:paragraph -->
  
  <!-- wp:paragraph -->
  <p><p id="anchor">Paragraph with anchor</p></p>
  <!-- /wp:paragraph -->
  
  <!-- wp:heading -->
  <h2 class="wp-block-heading">Heading without anchor</h2>
  <!-- /wp:heading -->
  
  <!-- wp:heading {"anchor":"anchor"} -->
  <h2 class="wp-block-heading" id="anchor">Heading with anchor</h2>
  <!-- /wp:heading -->
  
  <!-- wp:group {"layout":{"type":"constrained"}} /-->
  }}
  
  Issues:
  * The paragraph block with the anchor are nested in the `p` element
  * A comment about `anchor` attributes has been added to the heading block
  * The anchor in the group block are missing
  
  
    **Test Report Icons:**
    🐞 <= Indicates where issue ("bug") occurs.
    ✅ <= Behavior is ''expected''.
    ❌ <= Behavior is ''NOT expected''.
  

[hellofromTonya]

Test Report: Reproduce bug (before PR 4148 is applied) 🐞

[hellofromTonya]

Test Report: After applying PR 4148 - resolves the bug ✅

[hellofromTonya]

Test Report

Patch tested: ​https://github.com/WordPress/wordpress-develop/pull/4148

Environment

• OS: macOS
• Localhost: wp-env (Docker)
• Browser: Chrome
• Plugins: none
• Theme: TT3
• WordPress: trunk

Actual Results

When reproducing a bug/defect:

• ❌ Able to reproduce the issue as shown in trac57830-before-fix-applied.gif​

When testing the bugfix patch:

• ✅ The patch resolves the issue as shown in Trac57830-after-applying-fix.gif​

[hellofromTonya]

Prepping the commit

[hellofromTonya]

In 55443:

Editor: Partial revert of r55230.

[55230] introduced a regression to the content markup. This changeset is a partial revert to remove the added wp-includes/block-supports/anchor.php file.

The change of adding 'id' to $attributes_to_merge in get_block_wrapper_attributes() is not reverted as this change did not impact the regression and helps to support continue development in Gutenberg for the anchor support in dynamic blocks feature.

Reference:

• ​Gutenberg PR 48592.

Follow-up [55230].

Props wildworks, mamaduka, hellofromTonya.
Fixes #57830.
See #56852.

Committed via https://core.trac.wordpress.org/changeset/55443.