test: remove an unnecessary undefined in wpt

PR-URL: #41470
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Qingyu Deng <i@ayase-lab.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/common/wpt.js

@@ -78,7 +78,7 @@ class ResourceLoader {
 }
 
 class StatusRule {
-  constructor(key, value, pattern = undefined) {
+  constructor(key, value, pattern) {
     this.key = key;
     this.requires = value.requires || [];
     this.fail = value.fail;