COMP: Constructor initialize list improvement

Do not perform polymorphic class before this object is
constructed. Use Superclass::GetMeasurementVectorSize, as the parent
is already constructed at this point.

Thanks to Brad L for this fix.

Change-Id: I8267076cb5adfbae093d838b2eee68aec44a96aa
Merge topic 'HistogramConstructor'

81dc82f3 COMP: Constructor initialize list improvement