OUString: use startsWith, plus minor optimization
OUString: use startsWith, plus minor optimization

Change-Id: I883d9c3fa1e31791dfcae73b9e551e97440db647

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