Roll Dart SDK from f997d62a6d29 to 20bf2fcf5670 (18 revisions)

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': 'f997d62a6d29fa23ca140a60bba987fac7251c56',
+  'dart_revision': '20bf2fcf567074d087d977cfbfb469e7fe766023',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -170,7 +170,7 @@ deps = {
    Var('dart_git') + '/args.git' + '@' + Var('dart_args_tag'),
 
   'src/third_party/dart/third_party/pkg/async':
-   Var('dart_git') + '/async.git@e0c41e0c1fb70ba606dc81335c981af7c00987c6',
+   Var('dart_git') + '/async.git@5a4373458bfc902e4a4064427c619c2b41783f0d',
 
   'src/third_party/dart/third_party/pkg/bazel_worker':
    Var('dart_git') + '/bazel_worker.git@26680d5e249b249c7216ab2fed0ac8ed4ee285c5',
@@ -245,7 +245,7 @@ deps = {
    Var('dart_git') + '/markdown.git@dd150bb64c5f3b41d31f20f399ae2a855f7f8c00',
 
   'src/third_party/dart/third_party/pkg/matcher':
-   Var('dart_git') + '/matcher.git@af4fe7daf8e94a46981e4f072872be550a6969e9',
+   Var('dart_git') + '/matcher.git@8f8d965933c94a489b1a39e20d558a32841bfa5b',
 
   'src/third_party/dart/third_party/pkg/mime':
    Var('dart_git') + '/mime.git@179b5e6a88f4b63f36dc1b8fcbc1e83e5e0cd3a7',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: e575ad17a116204a303fd87eeb77de26
+Signature: 85932205c4f2a2abd9ccf1fb28e2a719
 
 UNUSED LICENSES: