don't use temporary object

This avoids invalid memory access with fdo45268-1.xlsx

Change-Id: If141df14d7d747023c944c83c2d8957abe8b95ad
avoid access to ChartView after having been deleted

e.g. 49225-3.xlsx

Change-Id: I62f2c39a928619ccfa66f128577de2c71f243a1c
fix invalid memory access related to temporary object

e.g. export of ooo116460-2.xlsx

Change-Id: Id1ca2249e7b1f197a2df0d122c57dd97c4c4d785