Roll src/third_party/dart bc9348829ef8..fc3af737c759 (2 commits) (#15965)

https://dart.googlesource.com/sdk.git/+log/bc9348829ef8..fc3af737c759

git log bc9348829ef8..fc3af737c759 --date=short --first-parent --format='%ad %ae %s'
2020-01-24 lrn@google.com Update typed-data constructor documentation.
2020-01-24 cskau@google.com [SDK] Fixes async* stack unwinding.

Created with:
  gclient setdep -r src/third_party/dart@fc3af737c759

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter-engine
Please CC dart-vm-team@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

Bug: None
Tbr: dart-vm-team@google.com

DEPS

@@ -34,7 +34,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'bc9348829ef833c8dc91d6f13f847afa51c63947',
+  'dart_revision': 'fc3af737c75931908521e9c36358a151408d6084',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

ci/licenses_golden/licenses_third_party

-Signature: 7fa1afb5ee6f2f5e525dee6d6414741f
+Signature: d35b19eb9daf521e4c322dfe55a63a04
 
 UNUSED LICENSES: