Convert bookmaker to SkJSON Verified that running bookmaker produces an identical fiddle.json before and after this change. Bug: skia: Change-Id: I1aa7477348a5f8c362201199b130508c2818116f Reviewed-on: https://skia-review.googlesource.com/c/188303 Commit-Queue: Brian Osman <brianosman@google.com> Reviewed-by: Florin Malita <fmalita@chromium.org>