Roll Dart SDK from b98a1ee to 6ecae20 (1 revision)

https://dart.googlesource.com/sdk.git/+log/b98a1eec5eb5..6ecae204598d

2021-05-01 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.14.0-70.0.dev

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/+doc/master/autoroll/README.md

Author: skia-flutter-autoroll

DEPS

@@ -35,7 +35,7 @@ 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': 'b98a1eec5eb5727f6d211b08daf5c2b5fe27d072',
+  'dart_revision': '6ecae204598d0c3767786b96f6e759523b0a7d3a',
 
   # 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

@@ -1,4 +1,4 @@
-Signature: 718f8841031abaf0593c0a9587ba2858
+Signature: 0cd97bc3f34ac40583de63d2f282fdba
 
 UNUSED LICENSES: