i#105557: more thread-safe caching of SwXFrame instances
i#105557: more thread-safe caching of SwXFrame instances

There's another over-engineered factory function to convert...

Change-Id: I4a51ea197f1a550f712f6542a4ebaf305e293f3f

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