--- a/dom/media/TextTrackList.cpp
+++ b/dom/media/TextTrackList.cpp
@@ -26,17 +26,16 @@ NS_INTERFACE_MAP_END_INHERITING(DOMEvent
 TextTrackList::TextTrackList(nsPIDOMWindowInner* aOwnerWindow)
   : DOMEventTargetHelper(aOwnerWindow)
 {
 }
 
 TextTrackList::TextTrackList(nsPIDOMWindowInner* aOwnerWindow,
                              TextTrackManager* aTextTrackManager)
   : DOMEventTargetHelper(aOwnerWindow)
-  , mPendingTextTrackChange(false)
   , mTextTrackManager(aTextTrackManager)
 {
 }
 
 TextTrackList::~TextTrackList()
 {
 }
 

--- a/dom/media/TextTrackList.h
+++ b/dom/media/TextTrackList.h
@@ -62,17 +62,17 @@ public:
   nsresult DispatchTrackEvent(nsIDOMEvent* aEvent);
   void CreateAndDispatchChangeEvent();
   void SetCuesInactive();
 
   IMPL_EVENT_HANDLER(change)
   IMPL_EVENT_HANDLER(addtrack)
   IMPL_EVENT_HANDLER(removetrack)
 
-  bool mPendingTextTrackChange;
+  bool mPendingTextTrackChange = false;
 
 private:
   ~TextTrackList();
 
   nsTArray< RefPtr<TextTrack> > mTextTracks;
   RefPtr<TextTrackManager> mTextTrackManager;
 
   void CreateAndDispatchTrackEventRunner(TextTrack* aTrack,