Roll external/skia 9a370396f..114bde830 (2 commits)

https://skia.googlesource.com/skia.git/+log/9a370396f..114bde830

2018-11-21 reed@google.com Revert "Revert "add rect-parameter to makeImageSnapshot""
2018-11-21 brianosman@google.com Revert "Prefer GrAAConvexPathRenderer over ccpr"

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https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

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Change-Id: Ifa939c91dfc3e258649edeebcd2c8a9adf451009
Exempt-From-Owner-Approval: The autoroll bot does not require owner approval.