Roll engine 55406841525f..6a5cbbdb4fc1 (2 commits) (#38770)

git@github.com:flutter/engine.git/compare/55406841525f...6a5cbbdb4fc1

git log 55406841525f..6a5cbbdb4fc1 --no-merges --oneline
2019-08-18 skia-flutter-autoroll@skia.org Roll src/third_party/skia 174ea86fa6c5..daa26335bb6a (1 commits) (flutter/engine#11138)
2019-08-18 skia-flutter-autoroll@skia.org Roll src/third_party/skia 4b567cd679ab..174ea86fa6c5 (1 commits) (flutter/engine#11127)

The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (stuartmorgan@google.com), and stop
the roller if necessary.

bin/internal/engine.version

-55406841525fba0dcb7fdf417bf021e96093459d
+6a5cbbdb4fc111b7be711e2d8bfbc8a336895c38