Blocks: Remove client-side polyfill for 'selectors' (WordPress#60846)

* Blocks: Remove client-side polyfill for 'selectors'
* Remove polyfill's unit test

Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>

packages/blocks/src/api/test/registration.js

@@ -398,43 +398,6 @@ describe( 'blocks', () => {
  } );
  } );
 
- // This can be removed once polyfill adding selectors has been removed.
- it( 'should apply selectors on the client when not set on the server', () => {
- const blockName = 'core/test-block-with-selectors';
- unstable__bootstrapServerSideBlockDefinitions( {
- [ blockName ]: {
- category: 'widgets',
- },
- } );
- unstable__bootstrapServerSideBlockDefinitions( {
- [ blockName ]: {
- selectors: { root: '.wp-block-custom-selector' },
- category: 'ignored',
- },
- } );
-
- const blockType = {
- title: 'block title',
- };
- registerBlockType( blockName, blockType );
- expect( getBlockType( blockName ) ).toEqual( {
- name: blockName,
- save: expect.any( Function ),
- title: 'block title',
- category: 'widgets',
- icon: { src: BLOCK_ICON_DEFAULT },
- attributes: {},
- providesContext: {},
- usesContext: [],
- keywords: [],
- selectors: { root: '.wp-block-custom-selector' },
- supports: {},
- styles: [],
- variations: [],
- blockHooks: {},
- } );
- } );
-
  // This test can be removed once the polyfill for blockHooks gets removed.
  it( 'should polyfill blockHooks using metadata on the client when not set on the server', () => {
  const blockName = 'tests/hooked-block';

packages/blocks/src/store/reducer.js

@@ -66,19 +66,6 @@ function bootstrappedBlockTypes( state = {}, action ) {
  // Don't overwrite if already set. It covers the case when metadata
  // was initialized from the server.
  if ( serverDefinition ) {
- // The `selectors` prop is not yet included in the server provided
- // definitions and needs to be polyfilled. This can be removed when the
- // minimum supported WordPress is >= 6.3.
- if (
- serverDefinition.selectors === undefined &&
- blockType.selectors
- ) {
- newDefinition = {
- ...serverDefinition,
- selectors: blockType.selectors,
- };
- }
-
  // The `blockHooks` prop is not yet included in the server provided
  // definitions and needs to be polyfilled. This can be removed when the
  // minimum supported WordPress is >= 6.4.