Bug 1584034: Fix assert failure when inJit is invoked directly from runqueue (outside of JS context). r=tcampbell

Differential Revision: https://phabricator.services.mozilla.com/D47260

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

js/src/builtin/TestingFunctions.cpp

@@ -2955,7 +2955,13 @@ static bool testingFunc_inJit(JSContext* cx, unsigned argc, Value* vp) {
 
   // Use frame iterator to inspect caller.
   FrameIter iter(cx);
-  MOZ_ASSERT(!iter.done());
+
+  // We may be invoked directly, not in a JS context, e.g. if inJit is added as
+  // a callback on the event queue.
+  if (iter.done()) {
+    args.rval().setBoolean(false);
+    return true;
+  }
 
   if (iter.hasScript()) {
     // Detect repeated attempts to compile, resetting the counter if inJit

js/src/jit-test/tests/modules/bug1584034.js

@@ -0,0 +1 @@
+import('./asdf.js').then(() => {}, inJit)