Roll external/skia 0191ed8e8..6dcbb9002 (5 commits)

https://skia.googlesource.com/skia.git/+log/0191ed8e8..6dcbb9002

2018-09-18 caryclark@skia.org fix conic fuzz
2018-09-18 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 95277a300f52..0fdb956d9c24 (1 commits)
2018-09-18 mtklein@google.com Reland "implement SkPixmap::erase() with draws"
2018-09-18 robertphillips@google.com Fix DDL reattachment of uniquely keyed proxies
2018-09-18 robertphillips@google.com Revert "Suppress addition of changeListeners during DDL recording"

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Change-Id: Ifcd362b13bd302a639805b9e9425e16e9c871774
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