writerfilter: not every field has a Content property
writerfilter: not every field has a Content property

... so don't try to get it unconditionally  (but SetExpression does
have it).

(regression from c7e4264bed4e77daccf2f72063e5e00f1008c3cf)

Change-Id: I14d24bd70f569ba0bc4f1e48d56ebf43c1441783

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