Roll engine f4b2183f1b97..6e506fb64147 (2 commits) (#49675)

https://github.com/flutter/engine/compare/f4b2183f1b97...6e506fb64147

git log f4b2183f1b97..6e506fb64147 --first-parent --oneline
2020-01-29 skia-flutter-autoroll@skia.org Roll src/third_party/skia 9ae06637d069..dcc8c5431bcb (16 commits) (flutter/engine#16173)
2020-01-29 mouad.debbar@gmail.com [web] Text width should never exceed constraint width (flutter/engine#16152)


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 cbracken@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

-f4b2183f1b9720824ba894d26477d2c0e864f7eb
+6e506fb641473408178e626dba40c8cec594d965