Roll src/third_party/dart 7408ed4730..7ebc820ffc (20 commits)

dart-lang/sdk@7ebc820ffc [CFE] Also guard _extensions for LazyScope
dart-lang/sdk@a196d68145 Revert "[vm, front-end server] Cache generated bytecode using separate file"
dart-lang/sdk@b2fa458f3d [CFE] Support experiments in the incremental compiler tests
dart-lang/sdk@da561313c6 [vm/bytecode] Erase promoted bounds of type parameter types
dart-lang/sdk@be6e5d8717 [vm] Try to symbolize Dart frames on crash or assertion failure when there is an exit frame.
dart-lang/sdk@804706c026 Represent variance as an object rather than an integer
dart-lang/sdk@782b048625 Bump the ABI version
dart-lang/sdk@a26f8402e5 [dartdevc] Branch the logic for FutureOr type tests when NNBD is enabled
dart-lang/sdk@f9969cca58 Add Element.declaration to unify elements and members.
dart-lang/sdk@b4ab28fef1 [vm/bytecode] Do not declare receiver variable in closures
dart-lang/sdk@cd6dbad074 [front-end server] Cleanup --strong in test/frontend_server_flutter.dart
dart-lang/sdk@6cde7ce224 Deprecate synthetic FunctionTypeImpl constructor.
dart-lang/sdk@86641d07ae [vm, front-end server] Cache generated bytecode using separate file
dart-lang/sdk@b5110a59a9 Revert "[vm/async] Don't add an <asynchronous suspension> marker along sync-async calls."
dart-lang/sdk@263ac017be Use standard Set in LegacyTypeAsserter.
dart-lang/sdk@c98df62dd0 [CFE] Add comments to clarify source encoding and offsets
dart-lang/sdk@1d6584720b Migrating DDC dart:developer patch files.
dart-lang/sdk@830b3d5f36 [front-end server] Remove obsolete --strong option
dart-lang/sdk@f4d930997b [vm/async] Don't add an <asynchronous suspension> marker along sync-async calls.
dart-lang/sdk@4366afc6f5 [http] noFolding() should follow same check as add()

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': '7408ed473006eeb41e23b9b21d2f5544bdd22b7b',
+  'dart_revision': '7ebc820ffcc06e08c0647b0a5e0f3bd41a967cf3',
 
   # 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: c56797567c2eb8b80b7d17fddc26d426
+Signature: 03d479e89fa6c0abff5498a9980dfd24
 
 UNUSED LICENSES: