Roll engine 51bdf834203c..05a0074580e1 (2 commits) (#38955)

git@github.com:flutter/engine.git/compare/51bdf834203c...05a0074580e1

git log 51bdf834203c..05a0074580e1 --no-merges --oneline
2019-08-21 skia-flutter-autoroll@skia.org Roll src/third_party/skia aa3820a9123c..0b9801eadc12 (3 commits) (flutter/engine#11334)
2019-08-21 dnfield@google.com Add tests for platform views (flutter/engine#11319)

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bin/internal/engine.version

-51bdf834203c6865054f8d2339fa9d1f2711a8d8
+05a0074580e1e3ae45bc6df6f2b28db097458ac8