FIX: We don't select 2D annotations.

When trying to select a 2D annotation ParaView segfaults in
vtkInternals::ConvertSelection. This segfault comes from
GetPixelInformation when this->Convert returns the color of a pixel
(instead of an actorid) for a 2D annotation so info.Prop is set to NULL.

Change-Id: Ia764ab7ff88f54dcf82040cbd64ecbcab9365573
Merge topic 'map-scalars-14943' into master

8c7db600 FIX: We don't select 2D annotations.