Bug 1927125 - Avoid triggering gray unmarking when unlinking module s…

…cripts r=sfink, a=dmeehan

Differential Revision: https://phabricator.services.mozilla.com/D226902

js/loader/LoadedScript.cpp

@@ -282,13 +282,13 @@ void ModuleScript::UnlinkModuleRecord() {
   // Remove the module record's pointer to this object if present and decrement
   // our reference count. The reference is added by SetModuleRecord() below.
   //
-  // This takes care not to trigger gray unmarking because this takes a lot of
-  // time when we're tearing down the entire page. This is safe because we are
-  // only writing undefined into the module private, so it won't create any
-  // black-gray edges.
   if (mModuleRecord) {
-    if (JS::IsCyclicModule(mModuleRecord)) {
-      JSObject* module = mModuleRecord.unbarrieredGet();
+    // Take care not to trigger gray unmarking because this takes a lot of time
+    // when we're tearing down the entire page. This is safe because we are only
+    // writing undefined into the module private, so it won't create any
+    // black-gray edges.
+    JSObject* module = mModuleRecord.unbarrieredGet();
+    if (JS::IsCyclicModule(module)) {
       MOZ_ASSERT(JS::GetModulePrivate(module).toPrivate() == this);
       JS::ClearModulePrivate(module);
     }