Use line numbers for test IDs

Line numbers are stable even if we skip tests

tests/phpunit/tests/html-api/wpHtmlProcessorHtml5lib.php

@@ -82,11 +82,9 @@ public function data_external_html5lib_tests() {
 			}
 
 			foreach ( self::parse_html5_dat_testfile( $test_dir . $entry ) as $k => $test ) {
-				// 1-index our test cases for printing
-				$case = $k + 1;
 				// strip .dat extension from filename
 				$test_suite = substr( $entry, 0, strlen( $entry ) - 4 );
-				yield "{$test_suite}/case{$case} - line {$test[0]}" => array_slice( $test, 1 );
+				yield "{$test_suite}/line{$test[0]}" => array_slice( $test, 1 );
 			}
 		}
 		closedir( $handle );