diff --git a/dom/base/ScriptSettings.cpp b/dom/base/ScriptSettings.cpp
index 550b25148c5..5db474c7f4c 100644
--- a/dom/base/ScriptSettings.cpp
+++ b/dom/base/ScriptSettings.cpp
@@ -517,10 +517,14 @@ AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
   , ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ true)
   , mWebIDLCallerPrincipal(nullptr)
   , mDocShellForJSRunToCompletion(nullptr)
+  , mIsMainThread(aIsMainThread)
 {
   MOZ_ASSERT(aGlobalObject);
   MOZ_ASSERT_IF(!aCx, aIsMainThread); // cx is mandatory off-main-thread.
   MOZ_ASSERT_IF(aCx && aIsMainThread, aCx == FindJSContext(aGlobalObject));
+  if (aIsMainThread) {
+    nsContentUtils::EnterMicroTask();
+  }
 
   if (aIsMainThread && gRunToCompletionListeners > 0) {
     nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aGlobalObject);
@@ -540,6 +544,10 @@ AutoEntryScript::~AutoEntryScript()
     mDocShellForJSRunToCompletion->NotifyJSRunToCompletionStop();
   }
 
+  if (mIsMainThread) {
+    nsContentUtils::LeaveMicroTask();
+  }
+
   // GC when we pop a script entry point. This is a useful heuristic that helps
   // us out on certain (flawed) benchmarks like sunspider, because it lets us
   // avoid GCing during the timing loop.
diff --git a/dom/base/ScriptSettings.h b/dom/base/ScriptSettings.h
index 4debd1ae091..5df78e23024 100644
--- a/dom/base/ScriptSettings.h
+++ b/dom/base/ScriptSettings.h
@@ -344,6 +344,8 @@ private:
   friend nsIPrincipal* GetWebIDLCallerPrincipal();
 
   nsIDocShell* mDocShellForJSRunToCompletion;
+
+  bool mIsMainThread;
 };
 
 /*