DOCX export: Write contextualSpacing only if it takes place.
DOCX export: Write contextualSpacing only if it takes place.

Change-Id: Ibc5783aeea8bcdc05c14054fa10c43a0c98c2159

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core