[REG 4.2 -> 4.3] QML files disappear from Projects view when refactoring

1. Create a new Qt Quick Application project using defaults.
2. Show the Projects view.
3. If needed, expand the project tree.
4. In the project's file main.qml, right-click on "MainForm".
5. From the context menu, select "Refactoring" -> " Move Component into Separate File".
   A dialog shows up.
6. Click "OK".
7. Click into the Projects view.
   The QML files will disappear from the Projects view. Their tree nodes are still there, but they don't contain any text and can't be used.

No files should disappear from the project tree. Only the new file should be added.

Found by Squish test tst_QMLS04.