wayland/dnd-surface: Scale DnD-surface-actor content if necessary
Since the recent clutter-content work, legacy scaling (in contrast to the new stage-view-scaling) only applies to surfaces that belong to a window. This broke scaling of DnD surfaces.
As a workaround, apply the same scaling on DnD-surface-actors until we use stage-view-scaling by default and can remove this again.
Fixes #685 (closed)
Edited by Robert Mader