If RunThreadPlan is called on a thread that doesn't have a selected frame, select frame 0.

<rdar://problem/13093321>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@175573 91177308-0d34-0410-b5e6-96231b3b80d8
Fixing a potential crasher where a synthetic value could return itself as its static value

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@175574 91177308-0d34-0410-b5e6-96231b3b80d8