If the StepThrough plan makes it back to the frame in which it started, it should say
it succeeded, since the plan that was using it can figure out what to do from there.
It should only say it failed if it truely went off into the weeds.

<rdar://problem/15597807>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@196631 91177308-0d34-0410-b5e6-96231b3b80d8