Bug 1567292 - Shutdown the mutex checking code in worker threads r=tcampbell

Differential Revision: https://phabricator.services.mozilla.com/D38963

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

js/src/shell/js.cpp

@@ -3985,6 +3985,8 @@ static bool ShellBuildId(JS::BuildIdCharVector* buildId);
 static void WorkerMain(WorkerInput* input) {
   MOZ_ASSERT(input->parentRuntime);
 
+  auto mutexShutdown = mozilla::MakeScopeExit([] { Mutex::ShutDown(); });
+
   JSContext* cx = JS_NewContext(8L * 1024L * 1024L, 2L * 1024L * 1024L,
                                 input->parentRuntime);
   if (!cx) {