Roll src/third_party/dart 275a76f2fcd8..dcdc71d7639a (31 commits) (#17562)

https://dart.googlesource.com/sdk.git/+log/275a76f2fcd8..dcdc71d7639a

git log 275a76f2fcd8..dcdc71d7639a --date=short --first-parent --format='%ad %ae %s'
2020-04-07 scheglov@google.com Report CONFLICTING_GENERIC_INTERFACES using ClassHierarchy.
2020-04-07 eernst@google.com Adjust member signature expectations for mixed inheritance
2020-04-07 kustermann@google.com [vm/compiler] Move runtime call of Throw/ReThrow/AssertBoolean/InstanceOf out into a Stub
2020-04-07 cskau@google.com [Compiler] Adds a set of generic AllocateObject stubs.
2020-04-07 scheglov@google.com Update constants_2018/constant_types_test to allow type parameters in 'as'.
2020-04-07 alexmarkov@google.com [vm/tests] Speed up / filter slow vm/dart/minimal_kernel*_test
2020-04-07 leafp@google.com Add tests for extended GLB.
2020-04-07 sra@google.com [dart2js] createFromStaticType for LegacyType
2020-04-07 rnystrom@google.com Migrate language_2/covariant to NNBD.
2020-04-07 srujzs@google.com [dart:html] Fix named args in js_typed_interop tests
2020-04-06 rnystrom@google.com Migrate language_2/constants_2018 to NNBD.
2020-04-06 scheglov@google.com Update language/constructor/return_test
2020-04-06 scheglov@google.com Update ClassHierarchy for legacy support, record errors.
2020-04-06 rmacnak@google.com Revert "[vm, gc] Parallel scavenge."
2020-04-06 srujzs@google.com [dart:html] Add nullability to item type for lists
2020-04-06 srujzs@google.com [dart:html] Remove 2.7 annotation from lib/html
2020-04-06 srujzs@google.com [dart:html] Migrate tests with only null asserts
2020-04-06 srujzs@google.com [dart:html] Migrate tests that need changes to NNBD
2020-04-06 srujzs@google.com [dart:html] Migrate more js tests to NNBD
2020-04-06 srujzs@google.com [dart:html] Migrate html tests with dynamic list conversions
2020-04-06 srujzs@google.com [dart:html] Migrate htmlcollection_test to null-safe
2020-04-06 rmacnak@google.com [vm, gc] Parallel scavenge.
2020-04-06 jwren@google.com Update the completion_metrics.dart algorithm to have 2 overlay options
2020-04-06 scheglov@google.com Clear class hierarchies to reduce memory consumption.
2020-04-06 rileyporter@google.com [tests] Removing more List constructor usage in corelib tests.
2020-04-06 liama@google.com [vm] Fix bug in late field reloading
2020-04-06 mfairhurst@google.com [nnbd_migration] Add sanity checks before writing to disk.
2020-04-06 mfairhurst@google.com [nnbd_migration] Change edit links to buttons.
2020-04-06 mehmetf@google.com Reland "[dart:_http] Allow the embedder to prohibit HTTP traffic."
2020-04-06 rmacnak@google.com [vm] Include the handler function in HandleMessage timeline events.
2020-04-06 scheglov@google.com Allow potentially constant type expression in 'as'.

Created with:
  gclient setdep -r src/third_party/dart@dcdc71d7639a

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/+/master/autoroll/README.md

Bug: None
Tbr: dart-vm-team@google.com

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': '275a76f2fcd879042cdca1d8d9a6f2c1dad4b4f9',
+  'dart_revision': 'dcdc71d7639ae83e011cc8d43121397021e35d08',
 
   # 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: 1f4f76e288d7a69844dd6193c60b2cb3
+Signature: 6ff2f5c3f9547985386c5d29d4246044
 
 UNUSED LICENSES:
 
@@ -7796,9 +7796,11 @@ FILE: ../../../third_party/dart/runtime/vm/visitor.cc
 FILE: ../../../third_party/dart/samples/ffi/async/async_test.dart
 FILE: ../../../third_party/dart/samples/ffi/async/sample_async_callback.dart
 FILE: ../../../third_party/dart/samples/ffi/async/sample_native_port_call.dart
+FILE: ../../../third_party/dart/sdk/lib/_http/embedder_config.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_dev_runtime/patch/js_patch.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/js_patch.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/vm/lib/ffi_struct_patch.dart
+FILE: ../../../third_party/dart/sdk_nnbd/lib/_http/embedder_config.dart
 FILE: ../../../third_party/dart/sdk_nnbd/lib/_internal/js_dev_runtime/patch/js_patch.dart
 FILE: ../../../third_party/dart/sdk_nnbd/lib/_internal/js_runtime/lib/js_patch.dart
 FILE: ../../../third_party/dart/sdk_nnbd/lib/_internal/vm/lib/ffi_struct_patch.dart