Roll engine 869b74eb4eca..728e473f1a4b (2 commits) (#43652)

git@github.com:flutter/engine.git/compare/869b74eb4eca...728e473f1a4b

git log 869b74eb4eca..728e473f1a4b --no-merges --oneline
2019-10-28 garyq@google.com Pass LinearTextFlat to SkFont -  iOS13 letter spacing (flutter/engine#13321)
2019-10-28 skia-flutter-autoroll@skia.org Roll src/third_party/skia 428b5de64a08..18f5b1a6dd77 (1 commits) (flutter/engine#13387)


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 aaclarke@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

-869b74eb4eca0b39dc5e890e6b283a4e6ebc11aa
+728e473f1a4bce3f4a034474d81cc95b691c6cf0