Bug 1332845 - Remove listeners before other cleanup in MediaRecorder. r=jesup

There was an indirect race from destroying this MediaInputPort before removing
the direct listener.

MozReview-Commit-ID: 7rPzsLL4EvG

--HG--
extra : rebase_source : 6271778593079609119153ce8b81587a9188d8ba

dom/media/MediaRecorder.cpp

@@ -825,11 +825,6 @@ private:
       }
       mInputStream = nullptr;
     }
-    for (RefPtr<MediaInputPort>& inputPort : mInputPorts) {
-      MOZ_ASSERT(inputPort);
-      inputPort->Destroy();
-    }
-    mInputPorts.Clear();
 
     if (mTrackUnionStream) {
       if (mEncoder) {
@@ -855,6 +850,12 @@ private:
       mTrackUnionStream = nullptr;
     }
 
+    for (RefPtr<MediaInputPort>& inputPort : mInputPorts) {
+      MOZ_ASSERT(inputPort);
+      inputPort->Destroy();
+    }
+    mInputPorts.Clear();
+
     if (mMediaStream) {
       mMediaStream->UnregisterTrackListener(this);
       mMediaStream = nullptr;