Stack walking of inlined frames.

Be "true" to the stack visitor design, which seems to be:
1) Carry minimal state, so this CL just adds an inlining depth to it.
2) Compute needed information for each method, which is what GetDexPc,
   GetMethod, and GetVRegFromOptimized code do.

Change-Id: I3d14126766f12216a7b448ce856259f1e7f37395