tdf#91260: unit test for textbox shrinking
tdf#91260: unit test for textbox shrinking

When the textboxes extend beyond the page bottom, the fix for
tdf#91260 keeps the original vertical position of the text frame
by changing its height.

Change-Id: I691b46640876bd082bd83da1bbd43f1e33ec807d

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