Show the stack trace in the Debugger slide.

Right now it is non-interactible, but it's still useful for keeping
track of the flow of execution.

http://screen/4b6WMGdw6j32AGc

Change-Id: I978d9b441c15674c6cae508b123579021c2ecc46
Bug: skia:12666
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/484076
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
2 files changed