Bug 1037342: Close file descriptor in BluetoothSocket (under bluetooth2/), r=btian

Currently, BluetoothSocket leaks its file descriptor on close
operations. With this patch when Gecko closes an instance of
BluetoothSocket, the file descriptor is now closed as well.

dom/bluetooth2/bluedroid/BluetoothSocket.cpp

@@ -145,8 +145,7 @@ public:
     MOZ_ASSERT(!NS_IsMainThread());
     MOZ_ASSERT(!mShuttingDownOnIOThread);
 
-    RemoveWatchers(READ_WATCHER | WRITE_WATCHER);
-
+    Close(); // will also remove fd from I/O loop
     mShuttingDownOnIOThread = true;
   }