Bug 1828084 - Relax waitForMultiple ordering constraints. r=dom-worker-reviewers,jstutte

test_WorkerDebugger_frozen.xhtml had 2 bad things happening:
- It wasn't using `add_task` so thrown exceptions would not propagate to
  the test framework; the test is now modernized to use add_task.
- waitForMultiple was requiring an ordering which did not hold and the
  test had even been changed in a place to use `Promise.all()` already
  because of this.  waitForMultiple has been changed to Promise.all()
  because this seems to have been a systemic error.  In the cases where
  the ordering dependency was fine like pairs of waitForUnregister()
  and waitForDebuggerClose(), the specific ordering was meaningless.
  - I did not change all call-sites for blame reasons and to avoid
    perturbing the linter further.

Differential Revision: https://phabricator.services.mozilla.com/D191822

dom/workers/test/chrome.toml

@@ -82,7 +82,6 @@ skip-if = ["true"] # Frequent intermittent on QR platforms Bug 1454935
 ["test_WorkerDebugger_console.xhtml"]
 
 ["test_WorkerDebugger_frozen.xhtml"]
-skip-if = ["debug"] # Bug 1828084
 
 ["test_WorkerDebugger_promise.xhtml"]
 

dom/workers/test/dom_worker_helper.js

@@ -147,25 +147,10 @@ function waitForWorkerMessage(worker, message) {
 }
 
 function waitForMultiple(promises) {
-  return new Promise(function (resolve) {
-    let values = [];
-    for (let i = 0; i < promises.length; ++i) {
-      let index = i;
-      promises[i].then(function (value) {
-        is(
-          index + 1,
-          values.length + 1,
-          "Promise " +
-            (values.length + 1) +
-            " out of " +
-            promises.length +
-            " should be resolved."
-        );
-        values.push(value);
-        if (values.length === promises.length) {
-          resolve(values);
-        }
-      });
-    }
-  });
+  // There used to be old logic which expects promises to be resolved in
+  // succession, but where it seems like this was an incorrect assumption.
+  // Assuming this change sticks, bug 1861778 tracks removing this method
+  // entirely in favor of Promise.all at the call-sites or transform the callers
+  // into explicitly documented awaited sequences.
+  return Promise.all(promises);
 }

dom/workers/test/test_WorkerDebugger_frozen.xhtml

@@ -4,8 +4,7 @@
   http://creativecommons.org/publicdomain/zero/1.0/
 -->
 <window title="Test for WorkerDebugger with frozen workers"
-        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        onload="test();">
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
   <script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
@@ -20,11 +19,9 @@
     const WORKER1_URL = "WorkerDebugger_frozen_worker1.js";
     const WORKER2_URL = "WorkerDebugger_frozen_worker2.js";
 
-    function test() {
-      (async function() {
-        SimpleTest.waitForExplicitFinish();
-
-        SpecialPowers.pushPrefEnv({set:
+    add_task(
+      async function runTest() {
+        await SpecialPowers.pushPrefEnv({set:
           [["browser.sessionhistory.max_total_viewers", 10]]});
 
         let promise = waitForMultiple([
@@ -60,10 +57,8 @@
            "debugger for worker on page 1 should not be closed");
         is(dbg2.isClosed, true,
            "debugger for worker on page 2 should be closed");
-
-        SimpleTest.finish();
-      })();
-    }
+      }
+    );
 
   ]]>
   </script>