Classes/RestrictedExtendClasses: efficiency fix

The `AbstractClassRestrictionsSniff` class does quite a lot of processing before passing off to the `process_matched_token()` method, which can cause quite some overhead for a sniff like this, which is only interested in a class being extended, so let's make it so this sniff only listens to the `T_EXTENDS` token.

This should make the sniff significantly faster.

Author: jrfnl

WordPressVIPMinimum/Sniffs/Classes/RestrictedExtendClassesSniff.php

@@ -35,6 +35,20 @@ public function getGroups() {
 		];
 	}
 
+	/**
+	 * Returns an array of tokens this test wants to listen for.
+	 *
+	 * @return array<int|string>
+	 */
+	public function register() {
+		$targets = parent::register();
+		if ( empty( $targets ) ) {
+			return $targets;
+		}
+
+		return [ T_EXTENDS ];
+	}
+
 	/**
 	 * Process a matched token.
 	 *
@@ -46,13 +60,6 @@ public function getGroups() {
 	 * @return void
 	 */
 	public function process_matched_token( $stackPtr, $group_name, $matched_content ) {
-		$tokens = $this->phpcsFile->getTokens();
-
-		if ( $tokens[ $stackPtr ]['code'] !== T_EXTENDS ) {
-			// If not extending, bail.
-			return;
-		}
-
 		foreach ( $this->getGroups() as $group => $group_args ) {
 			$this->phpcsFile->{ 'add' . $group_args['type'] }( $group_args['message'], $stackPtr, $group );
 		}