rhbz#810644: CalcClipRect: add band-aid
rhbz#810644: CalcClipRect: add band-aid

No idea what the problem is, perhaps it'll just crash elsewhere now...

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