Coding Standards: Bring more consistency to PHP 8.0 string function polyfills.

This adjusts `str_contains()` code layout to have an early exit for an empty `$needle`, matching similar fragments in `str_starts_with()` and `str_ends_with()` for better readability.

Follow-up to [52039], [52040].

See #57839.

git-svn-id: https://develop.svn.wordpress.org/trunk@55726 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/compat.php

@@ -434,11 +434,15 @@ function array_key_last( array $array ) { // phpcs:ignore Universal.NamingConven
 	 * @since 5.9.0
 	 *
 	 * @param string $haystack The string to search in.
-	 * @param string $needle   The substring to search for in the haystack.
+	 * @param string $needle   The substring to search for in the `$haystack`.
 	 * @return bool True if `$needle` is in `$haystack`, otherwise false.
 	 */
 	function str_contains( $haystack, $needle ) {
-		return ( '' === $needle || false !== strpos( $haystack, $needle ) );
+		if ( '' === $needle ) {
+			return true;
+		}
+
+		return false !== strpos( $haystack, $needle );
 	}
 }