Fix bugs introduced by the display object sharing optimization. This checkin should fix ordering problems when dynamically adding/removing graphic elements, and ordering problems when changing graphic element properties that require a display object (rotation, alpha, filters, etc).
MXMLG-219: BitmapGraphic component content always rendered from 0, 0 origin.
MXMLG-220: setting visible property of Rect and Ellipse does nothing.
MXMLG-222: setting the alpha of a rectangle changes z-order when there are 3 or more rectangles
SDK-16754: Z-order incorrect when a Group is present
QA: Yes - the test files from these bugs (or something equivalent) should be added to our standard test suite