fixup! test: add opt-in process WPT runner

Author: panva

test/parallel/test-common-wpt-backends.js

@@ -77,8 +77,11 @@ async function collect(backend, throws) {
 }
 
 async function compare(throws) {
-  const thread = await collect('thread', throws);
-  const child = await collect('process', throws);
+  // Compared as a set: an uncaught error reaches the runner over a different
+  // channel than the results do, so it can overtake them on the thread
+  // backend. The runner acts on each of these independently.
+  const thread = (await collect('thread', throws)).sort();
+  const child = (await collect('process', throws)).sort();
   assert.notStrictEqual(thread.length, 0);
   assert.deepStrictEqual(thread, child);
   return thread;
@@ -99,7 +102,7 @@ function runDriver(driver, spec, backend) {
 
 async function main() {
   const completed = await compare(false);
-  assert.deepStrictEqual(completed.slice().sort(), [
+  assert.deepStrictEqual(completed, [
     'completion 0',
     'result 0 passes',
     'result 0 passes asynchronously',