Tests for undo in TextView fields with no cursor

This tests for a rare crash in the undo system. In particular, if the
TextView did not have a cursor and the first operation was a
programmatic insert/append the "old cursor position" would be -1.
Attempting to undo would try to restore the cursor to -1 and crash.

Code in question is in frameworks/base

Bug: 19332904
Change-Id: I66f4265ac1df38b3daa8c8ee2a416d6927f9405f