This can be used later for the VML or binary export of shapes imported
from drawingML. Note that without this, drawingML shapes won't be
exported to VML, as e.g. for a triangle it expects a
'isosceles-triangle' type, while the shype's type is 'ooxml-triangle'.

Change-Id: I59abc27febdd026c181a7ff38b16c93567058cb9