[css] use accesser function for ClutterActor:name rather than g_object_get
[css] use accesser function for ClutterActor:name rather than g_object_get

This avoids needing to copy and free the resulting string and removes the
performance overhead from using g_object_get.

clutter-project/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx