sw: convert DBG_ASSERTs in SwAccessibleParagraph
sw: convert DBG_ASSERTs in SwAccessibleParagraph

... and fix a copy-paste error and remove some pointlessly defensive
code.

Change-Id: I08e74a6bc843b307d1c8a7157c2a67f471c00522

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