Bug 1588002 - Make sure to remove every nsIDOMMozWakeLockListener added by browser_media_wakelock.js even if a notification is not seen. r=alwu

Differential Revision: https://phabricator.services.mozilla.com/D48931

--HG--
extra : moz-landing-system : lando

toolkit/content/tests/browser/browser.ini

@@ -156,9 +156,7 @@ support-files =
   file_videoWithoutAudioTrack.html
   gizmo.mp4
   gizmo-noaudio.webm
-skip-if =
-  (os == "win" && processor == "aarch64") || # aarch64 due to 1536573
-  (fission && debug) # Leaks the world under Fission.
+skip-if = (os == "win" && processor == "aarch64") # aarch64 due to 1536573
 [browser_mute.js]
 tags = audiochannel
 skip-if = (os == "win" && processor == "aarch64") # aarch64 due to 1536573

toolkit/content/tests/browser/browser_media_wakelock.js

@@ -35,10 +35,9 @@ function wakeLockObserved(observeTopic, checkFn) {
 
 function getWakeLockState(topic, needLock, isTabInForeground) {
   const tabState = isTabInForeground ? "foreground" : "background";
-  const promise = wakeLockObserved(
-    topic,
-    state => state == `locked-${tabState}`
-  );
+  const promise = needLock
+    ? wakeLockObserved(topic, state => state == `locked-${tabState}`)
+    : null;
   return {
     check: async () => {
       if (needLock) {