QmlDesigner: Remove unused class

Change-Id: Ia894e381251b56be44e56c9c798ec22713cbeabc
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
QmlDesigner: Fix potential null dereference

Change-Id: I291d07548bbbe7c7ab75dc55004e3c44c4bf0020
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>