Roll external/skia 600ed1266..ef4047db9 (12 commits)

https://skia.googlesource.com/skia.git/+log/600ed1266..ef4047db9

2018-11-28 reed@google.com add bench for computing convexity
2018-11-28 fmalita@chromium.org [skottie] Add a custom property manager util class
2018-11-28 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 83b2f0e8a2e0..c4e0a1e511fc (1 commits)
2018-11-28 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 67c93d206431..3b003a51bc9a (1 commits)
2018-11-28 reed@google.com Force clients to specify font when requesting strikecache
2018-11-28 egdaniel@google.com In Vulkan, use 1000 for maxLod instead of maxMipLevel when using mips.
2018-11-28 borenet@google.com Use LUCI trybots in update_meta_config
2018-11-28 reed@google.com rm SK_SUPPORT_LEGACY_TEXTBLOBBUILD_WITH_PAINT from fluter
2018-11-28 reed@google.com rm SK_SUPPORT_LEGACY_NESTED_HINTINGENUM from flutter
2018-11-28 reed@google.com Revert "don't trust convexity with affine transforms"
2018-11-28 reed@google.com Reland "Don't let neighboring radii in GrAAFillRRectOp get too close"
2018-11-28 reed@google.com Revert "Don't let neighboring radii in GrAAFillRRectOp get too close"

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Change-Id: Ic22ba05b8ff49275819ac86cf888c93a0ae38d21
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