Roll external/skia 70bd0b72f..61c510810 (6 commits)

https://skia.googlesource.com/skia.git/+log/70bd0b72f..61c510810

2018-10-24 mtklein@google.com serious SkEdgeBuilder refactoring
2018-10-24 caryclark@skia.org fix fuzz divide by zero
2018-10-24 csmartdalton@google.com ccpr: Fix an overzealous assert in DDL
2018-10-24 bsalomon@google.com Revert "Reland "Reland "Revert "Use OpenGL sampler objects when available.""""
2018-10-24 mtklein@google.com we don't need two ways to disable lowp
2018-10-24 mtklein@google.com remove src/jumper

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Change-Id: Iea592d00a635b46b7c1dfd971d59d657eaf2c1bb
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