Revert "Try abstract class instead of interface"

This reverts commit 74881651faf991eabceb090707ce8b43c2a25316.

src/wp-includes/html-api/class-wp-css-attribute-selector.php

@@ -1,6 +1,6 @@
 <?php
 
-final class WP_CSS_Attribute_Selector extends WP_CSS_HTML_Tag_Processor_Matcher {
+final class WP_CSS_Attribute_Selector implements WP_CSS_HTML_Tag_Processor_Matcher {
 	const WHITESPACE_CHARACTERS = " \t\r\n\f";
 
 	public function matches( WP_HTML_Tag_Processor $processor ): bool {

src/wp-includes/html-api/class-wp-css-class-selector.php

@@ -1,6 +1,6 @@
 <?php
 
-final class WP_CSS_Class_Selector extends WP_CSS_HTML_Tag_Processor_Matcher {
+final class WP_CSS_Class_Selector implements WP_CSS_HTML_Tag_Processor_Matcher {
 	public function matches( WP_HTML_Tag_Processor $processor ): bool {
 		return (bool) $processor->has_class( $this->ident );
 	}

src/wp-includes/html-api/class-wp-css-complex-selector-list.php

@@ -32,7 +32,7 @@
  *
  * @access private
  */
-class WP_CSS_Complex_Selector_List extends WP_CSS_Compound_Selector_List {
+class WP_CSS_Complex_Selector_List extends WP_CSS_Compound_Selector_List implements WP_CSS_HTML_Processor_Matcher {
 	/**
 	 * Takes a CSS selector string and returns an instance of itself or `null` if the selector
 	 * string is invalid or unsupported.

src/wp-includes/html-api/class-wp-css-complex-selector.php

@@ -5,7 +5,7 @@
  *
  * > <complex-selector> = <compound-selector> [ <combinator>? <compound-selector> ] *
  */
-final class WP_CSS_Complex_Selector extends WP_CSS_HTML_Processor_Matcher {
+final class WP_CSS_Complex_Selector implements WP_CSS_HTML_Processor_Matcher {
 	public function matches( WP_HTML_Processor $processor ): bool {
 		// First selector must match this location.
 		if ( ! $this->selectors[0]->matches( $processor ) ) {

src/wp-includes/html-api/class-wp-css-compound-selector-list.php

@@ -76,7 +76,7 @@
  * @link https://www.w3.org/TR/selectors-api2/
  * @link https://www.w3.org/TR/selectors-4/
  */
-class WP_CSS_Compound_Selector_List extends WP_CSS_HTML_Tag_Processor_Matcher {
+class WP_CSS_Compound_Selector_List implements WP_CSS_HTML_Tag_Processor_Matcher {
 	/**
 	 * @param WP_HTML_Tag_Processor $processor
 	 * @return bool

src/wp-includes/html-api/class-wp-css-compound-selector.php

@@ -5,7 +5,7 @@
  *
  * > <compound-selector> = [ <type-selector>? <subclass-selector>* ]!
  */
-final class WP_CSS_Compound_Selector extends WP_CSS_HTML_Tag_Processor_Matcher {
+final class WP_CSS_Compound_Selector implements WP_CSS_HTML_Tag_Processor_Matcher {
 	public function matches( WP_HTML_Tag_Processor $processor ): bool {
 		if ( $this->type_selector ) {
 			if ( ! $this->type_selector->matches( $processor ) ) {

src/wp-includes/html-api/class-wp-css-id-selector.php

@@ -1,6 +1,6 @@
 <?php
 
-final class WP_CSS_ID_Selector extends WP_CSS_HTML_Tag_Processor_Matcher {
+final class WP_CSS_ID_Selector implements WP_CSS_HTML_Tag_Processor_Matcher {
 	/** @var string */
 	public $ident;
 

src/wp-includes/html-api/class-wp-css-type-selector.php

@@ -1,6 +1,6 @@
 <?php
 
-final class WP_CSS_Type_Selector extends WP_CSS_HTML_Tag_Processor_Matcher {
+final class WP_CSS_Type_Selector implements WP_CSS_HTML_Tag_Processor_Matcher {
 	public function matches( WP_HTML_Tag_Processor $processor ): bool {
 		$tag_name = $processor->get_tag();
 		if ( null === $tag_name ) {

src/wp-includes/html-api/interface-wp-css-html-processor-matcher.php

@@ -1,8 +1,8 @@
 <?php
 
-abstract class WP_CSS_HTML_Processor_Matcher {
+interface WP_CSS_HTML_Processor_Matcher {
 	/**
 	 * @return bool
 	 */
-	abstract public function matches( WP_HTML_Processor $processor ): bool;
+	public function matches( WP_HTML_Processor $processor ): bool;
 }

src/wp-includes/html-api/interface-wp-css-html-tag-processor-matcher.php

@@ -1,8 +1,8 @@
 <?php
 
-abstract class WP_CSS_HTML_Tag_Processor_Matcher {
+interface WP_CSS_HTML_Tag_Processor_Matcher {
 	/**
 	 * @return bool
 	 */
-	abstract public function matches( WP_HTML_Tag_Processor $processor ): bool;
+	public function matches( WP_HTML_Tag_Processor $processor ): bool;
 }