Detect if polypolygon is a rectangle in DrawGradient
Detect if polypolygon is a rectangle in DrawGradient

If the polypolygon that we use for DrawGradient is a rectangle, then we
need to 1) expand the gradient rectangle to avoid missing lines on the
right and bottom edge, and 2) we should pass NULL as the clipping
parameter for ImplDrawLinearGradient and ImplDrawComplexGradient.

Change-Id: I8d8289ace069b5c500db59d1a2addfcea8388dfb

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