--- a/dom/events/EventListenerManager.cpp
+++ b/dom/events/EventListenerManager.cpp
@@ -280,16 +280,18 @@ EventListenerManager::AddEventListenerIn
   listener->mListener = aListenerHolder;
   listener->mEventMessage = aEventMessage;
   listener->mTypeString = aTypeString;
   listener->mTypeAtom = aTypeAtom;
   listener->mFlags = aFlags;
   listener->mListenerIsHandler = aHandler;
   listener->mHandlerIsString = false;
   listener->mAllEvents = aAllEvents;
+  listener->mIsChrome = mIsMainThreadELM &&
+    nsContentUtils::LegacyIsCallerChromeOrNativeCode();
 
   // Detect the type of event listener.
   nsCOMPtr<nsIXPConnectWrappedJS> wjs;
   if (aFlags.mListenerIsJSListener) {
     MOZ_ASSERT(!aListenerHolder.HasWebIDLCallback());
     listener->mListenerType = Listener::eJSEventListener;
   } else if (aListenerHolder.HasWebIDLCallback()) {
     listener->mListenerType = Listener::eWebIDLListener;
@@ -674,16 +676,25 @@ EventListenerManager::ListenerCanHandle(
     return true;
   }
   if (aEvent->mMessage == eUnidentifiedEvent) {
     if (mIsMainThreadELM) {
       return aListener->mTypeAtom == aEvent->mSpecifiedEventType;
     }
     return aListener->mTypeString.Equals(aEvent->mSpecifiedEventTypeString);
   }
+  if (!nsContentUtils::IsUnprefixedFullscreenApiEnabled() &&
+      aEvent->IsTrusted() && (aEventMessage == eFullscreenChange ||
+                              aEventMessage == eFullscreenError)) {
+    // If unprefixed Fullscreen API is not enabled, don't dispatch it
+    // to the content.
+    if (!aEvent->mFlags.mInSystemGroup && !aListener->mIsChrome) {
+      return false;
+    }
+  }
   MOZ_ASSERT(mIsMainThreadELM);
   return aListener->mEventMessage == aEventMessage;
 }
 
 void
 EventListenerManager::AddEventListenerByType(
                         const EventListenerHolder& aListenerHolder,
                         const nsAString& aType,

--- a/dom/events/EventListenerManager.h
+++ b/dom/events/EventListenerManager.h
@@ -190,16 +190,17 @@ public:
       eWebIDLListener,
       eListenerTypeCount
     };
     uint8_t mListenerType;
 
     bool mListenerIsHandler : 1;
     bool mHandlerIsString : 1;
     bool mAllEvents : 1;
+    bool mIsChrome : 1;
 
     EventListenerFlags mFlags;
 
     JSEventHandler* GetJSEventHandler() const
     {
       return (mListenerType == eJSEventListener) ?
         static_cast<JSEventHandler*>(mListener.GetXPCOMCallback()) :
         nullptr;