Roll src/third_party/skia f6703fa:73fa616

Roll src/third_party/skia f6703fa:73fa616

Summary of changes available at:
https://chromium.googlesource.com/skia/+log/f6703fa..73fa616

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=msarett@google.com

Commits in this roll:
73fa616 wangyix@google.com Added SkComposeShader GPU implementation
0ce744e mtklein@chromium.org CMake tweaks   - I think CMake 3.1 is enough for now.   - Ubuntu works too.
0a1fa5e hendrikw@chromium.org skia: Replace CommandBuffer_ with egl
c9a3706 robertphillips@google.com Limit lifetime of GrDrawContext objects
dac7005 joshualitt@chromium.org Remove GrGpuTraceMarker hooks until we rethink the design
aeb77ea wangyix@google.com GrGLBlend::AppendPorterDuffBlend now supports kClear_Mode
2dc2994 jvanverth@google.com Various minor cross-platform changes
c5281e5 mtklein@chromium.org SkColorCubeFilter_opts: rounding is actually free here.
6335a72 joshualitt@chromium.org Move PathRenderers to batches folder
fbccb59 msarett@google.com Call standard libjpeg/libjpeg-turbo APIs
a508f3c mtklein@chromium.org Require Sk4f::toBytes() clamps
580c40a caryclark@google.com link test to bug

Review URL: https://codereview.chromium.org/1313483003

Cr-Commit-Position: refs/heads/master@{#346696}