diff --git a/dom/base/ScriptSettings.cpp b/dom/base/ScriptSettings.cpp
index d7c26096da1..e02d1fc288f 100644
--- a/dom/base/ScriptSettings.cpp
+++ b/dom/base/ScriptSettings.cpp
@@ -463,14 +463,22 @@ AutoEntryScript::AutoEntryScript(nsIGlobalObject* aGlobalObject,
               aCx ? aCx : FindJSContext(aGlobalObject))
   , ScriptSettingsStackEntry(aGlobalObject, /* aCandidate = */ true)
   , mWebIDLCallerPrincipal(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();
+  }
 }
 
 AutoEntryScript::~AutoEntryScript()
 {
+  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 f6559a447e0..ffb78ae6f73 100644
--- a/dom/base/ScriptSettings.h
+++ b/dom/base/ScriptSettings.h
@@ -330,6 +330,7 @@ private:
   // bit up the stack, and which will outlive us.  So we know the principal
   // can't go away until then either.
   nsIPrincipal* mWebIDLCallerPrincipal;
+  bool mIsMainThread;
   friend nsIPrincipal* GetWebIDLCallerPrincipal();
 };