Roll engine ba1a303ae2d7..9f1eab2f1f26 (4 commits) (#39278)

git@github.com:flutter/engine.git/compare/ba1a303ae2d7...9f1eab2f1f26

git log ba1a303ae2d7..9f1eab2f1f26 --no-merges --oneline
2019-08-26 garyq@google.com Expose LineMetrics in dart:ui (flutter/engine#10670)
2019-08-26 dnfield@google.com Roll buildroot and update gn script for bitcode_marker (flutter/engine#11449)
2019-08-26 skia-flutter-autoroll@skia.org Roll src/third_party/skia d617d5d29ca5..464eb78e444b (10 commits) (flutter/engine#11444)
2019-08-26 skia-flutter-autoroll@skia.org Roll fuchsia/clang/mac-amd64 from RDjN2... to CGYQg... (flutter/engine#11442)


If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-engine-flutter-autoroll
Please CC liyuqian@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

bin/internal/engine.version

-ba1a303ae2d7873135d415f36dee75ce8174a73a
+9f1eab2f1f269299bb5ac3adb6b96a7291851327