Bug 1425559 - nsPrompter must use nsIThreadManager::spinEventLoopUntilOrShutdown, r=smaug

testing/web-platform/meta/webdriver/tests/execute_async_script/user_prompts.py.ini

@@ -1,7 +1,4 @@
 [user_prompts.py]
-  expected:
-    if debug: TIMEOUT # https://bugzilla.mozilla.org/show_bug.cgi?id=1425559
-
   [test_handle_prompt_accept]
     expected: FAIL
 

testing/web-platform/meta/webdriver/tests/execute_script/user_prompts.py.ini

@@ -1,7 +1,4 @@
 [user_prompts.py]
-  expected:
-    if debug: TIMEOUT # https://bugzilla.mozilla.org/show_bug.cgi?id=1425559
-
   [test_handle_prompt_accept]
     expected: FAIL
 

toolkit/components/prompts/src/nsPrompter.js

@@ -507,7 +507,7 @@ function openRemotePrompt(domWin, args, tabPrompt) {
 
     messageManager.sendAsyncMessage("Prompt:Open", args, {});
 
-    Services.tm.spinEventLoopUntil(() => closed);
+    Services.tm.spinEventLoopUntilOrShutdown(() => closed);
 }
 
 function ModalPrompter(domWin) {