remove toString

toString may have been used by obsolete debugger only
find out if that is so

R=brianosman@google.com,bsalomon@google.com

Docs-Preview: https://skia.org/?cl=119894
Bug:830651
Change-Id: I737f19b7d3fbc869bea2f443fa3b5ed7c1393ffd
Reviewed-on: https://skia-review.googlesource.com/119894
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
130 files changed