DM: JSON Debug Sink

Currently, the following GMs crash the debug canvas:
    ~dont_clip_to_layer
    ~imageblur
    ~imagefilterscropped
    ~pictureimagefilter
    ~savelayer_lcdtext
    ~textfilter_image
// TODO(halcanary): fix this.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3742

Change-Id: Ieed3502119cd639fe345f3a41d436d5e39f3bdf1
Reviewed-on: https://skia-review.googlesource.com/3742
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Hal Canary <halcanary@google.com>
3 files changed