Blender crashes with heap-use-after-free while editing curves or text objects with BI rendered mode enabled.

Steps to reproduce:
1) Add a text object
2) Turn on the Rendered viewport mode
3.1) Press Tab and type characters until blender crashes
3.2) Drag the Bevel slider in font settings also leads to crash
3.3) With curves: add bevel in curve settings and drag the bevel resolution sider until blender crashes
3.4) Also sometimes blender crashes while editing 2D cyclic curves.

The only common thing in these cases is the place of free in
do_makeDispListCurveTypes ./source/blender/blenkernel/intern/displist.c:1399
BLI_freelistN(&(cu->bev));

Tested with r58048.