Roll src/third_party/dart d50c158d42..bbe2ac28c9 (19 commits)

dart-lang/sdk@bbe2ac28c9 [dartdevc] Add runtime support for NNBD weak subtype checks
dart-lang/sdk@2f6de17113 Add extensions to LibraryElement.topLevelElements
dart-lang/sdk@b164a892e2 [vm] Fix spurious MSAN failures when accessing arguments to runtime calls.
dart-lang/sdk@fb362b54a7 Stop using FunctionTypeAliasElement.parameters/returnType in analyzer.
dart-lang/sdk@67a7aae567 [dartdevc] Adding logic for required named parameter runtime checks.
dart-lang/sdk@bbe273081c Report a diagnostic when the length getter in a constant expression is defined in an extension (issue 39170)
dart-lang/sdk@2b903a6bfd Add more subtype tests.
dart-lang/sdk@0722c39ffa [dart2js] Mark pkg/js_ast/test/printer_callback_test as slow.
dart-lang/sdk@44641fbd61 Added variance support in bounds inferencing.
dart-lang/sdk@f99a28407f [dartdevc] Temporarily run NNBD tests with a "hybrid" SDK
dart-lang/sdk@79900aea3a Remove AstBuilder.localDeclarations
dart-lang/sdk@e01ba33faf Remove CompilationUnitElementImpl.localDeclarations
dart-lang/sdk@948e1da54c Remove _HasTypedefSelfReferenceVisitor, already computed during linking.
dart-lang/sdk@4495165191 Always return some GenericFunctionTypeElement from GenericTypeAliasElementImpl.function
dart-lang/sdk@24ad18c51a NNBD ported developer.dart
dart-lang/sdk@33274b6fae [dartdevc] removed unnecessary '.bind(this)' + added doc comments.
dart-lang/sdk@262fadc6cf Change the type of RetainingPathItem.parentField to String in the observatory
dart-lang/sdk@48fbd1aa2b Throw exception when calling defaultDartType in VarianceCalculator.
dart-lang/sdk@7e76414eab [frontend_server] Support Fuchsia-style package splitting and FAR manifest generation.

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': 'd50c158d4275e23d14d845c93bb6755e218342f8',
+  'dart_revision': 'bbe2ac28c9ab5bfec4e13d5df9360e7aa691cfe6',
 
   # 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: 11e32382c56527efdcebb8a776a011be
+Signature: 10793d772d6c660b5fab347dc5ac6cf2
 
 UNUSED LICENSES:
 
@@ -7490,6 +7490,7 @@ FILE: ../../../third_party/dart/sdk/lib/vmservice_libraries.json
 FILE: ../../../third_party/dart/sdk_nnbd/lib/html/html_common/conversions_dart2js.dart
 FILE: ../../../third_party/dart/sdk_nnbd/lib/html/html_common/html_common.dart
 FILE: ../../../third_party/dart/sdk_nnbd/lib/libraries.json
+FILE: ../../../third_party/dart/sdk_nnbd/lib/libraries_nnbd_mix_hack.json
 FILE: ../../../third_party/dart/sdk_nnbd/lib/vmservice_libraries.json
 FILE: ../../../third_party/dart/third_party/7zip.tar.gz.sha1
 FILE: ../../../third_party/dart/third_party/clang.tar.gz.sha1