Refactor code in preparation of correct stack maps in slow path.

Move the logic of saving/restoring live registers in slow path
in the SlowPathCode method. Also add a RecordPcInfo helper to
SlowPathCode, that will act as the placeholder of saving correct
stack maps.

Change-Id: I25c2bc7a642ef854bbc8a3eb570e5c8c8d2d030c
9 files changed