Add an extra pixel to the distance field path renderer bounds.

Add an extra pixel to the distance field path renderer bounds.

Cherry-pick to M56

BUG=chromium:663701
BUG=skia:5989

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5086

Change-Id: Ie97f46b108f54c711c5928b11a9921be38356f8d
Reviewed-on: https://skia-review.googlesource.com/5086
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

Cherry-pick to M55

NOTREECHECKS=true
NOTRY=true
NOPRESUBMIT=true

Change-Id: I3f8e5de782846447c6f809c3284c5081b5d7a283
Reviewed-on: https://skia-review.googlesource.com/5267
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-on: https://skia-review.googlesource.com/6412