Roll Dart SDK from 704928da5702 to 1db2d4d95562 (1 revision) (#23846)

https://dart.googlesource.com/sdk.git/+log/704928da5702..1db2d4d95562

2021-01-22 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.12.0-251.0.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

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': '704928da5702cc773256df97169cea5b21e41c80',
+  'dart_revision': '1db2d4d9556296482a207f171b4d732dcd8e2432',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -47,7 +47,7 @@ vars = {
   'dart_http_retry_tag': '0.1.1',
   'dart_http_throttle_tag': '1.0.2',
   'dart_intl_tag': '0.17.0-nullsafety',
-  'dart_linter_tag': '0.1.128',
+  'dart_linter_tag': '0.1.129',
   'dart_oauth2_tag': '1.6.0',
   'dart_protobuf_rev': '0d03fd588df69e9863e2a2efc0059dee8f18d5b2',
   'dart_pub_rev': '392a3cb455af48f7ce8807a96174691945f97f0a',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 2555fb1c1b9be9971aef792eba563468
+Signature: 2ee89baba494eb7e60d8cc39e16c8f41
 
 UNUSED LICENSES: