Roll Dart SDK from 6607655 to a3d3777 (18 revisions)

https://dart.googlesource.com/sdk.git/+log/660765538200..a3d3777094ce

2020-07-16 [email protected] Migration: add a hook invoked after changes are applied.
2020-07-16 [email protected] [web] remove mirrors patch for web compilers.
2020-07-15 [email protected] [dart2js] Refractored ConstantValueTypeMasks
2020-07-15 [email protected] Modify parser to handle abstract fields.
2020-07-15 [email protected] bulk fixes impl
2020-07-15 [email protected] [dart2js] Port ~20 tests to nnbd #3.
2020-07-15 [email protected] [ package:dds ] Add missing package:shelf_static dependency in pubspec.yaml
2020-07-15 [email protected] Revert "Move `BytesBuilder` class and implementation to `dart:typed_data`."
2020-07-15 [email protected] [ package:dds ] Add server-sent event (SSE) support to DDS
2020-07-15 [email protected] Improve diagnostic message when short circuiting (issue 42599)
2020-07-15 [email protected] [ Service ] Fix line numbers in step_through_mixin_from_sdk_test
2020-07-15 [email protected] [ package:dds ] Fix issue where StateError could be thrown if DDS shuts down with in-flight requests
2020-07-15 [email protected] [vm/nnbd] Do not check if NNBD experimental flag is enabled for non-null assertions
2020-07-15 [email protected] Issue 42699. Stop reporting EXPORT_DUPLICATED_LIBRARY_NAMED and IMPORT_DUPLICATED_LIBRARY_NAMED.
2020-07-15 [email protected] [vm] Fix --use-bare-instructions=false on simarm_x64.
2020-07-15 [email protected] [vm] Add tests and packages to the Fuchsia package
2020-07-15 [email protected] Make CiderCacheEntry public.
2020-07-15 [email protected] [infra] Update Chrome used in testing to version 84

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
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Documentation for the AutoRoller is here:
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Author: skia-flutter-autoroll

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': '66076553820056eca190b9ffd84d2c7e29127d19',
+  'dart_revision': 'a3d3777094ce3b0feb09f6470a785b922218b774',
 
   # 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: 313f21a031a990c9a4046dfe176e04e4
+Signature: 95ae9578c50cccc1359eb86d0bfe3552
 
 UNUSED LICENSES:
 
@@ -8745,7 +8745,6 @@ FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/js_array.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/js_number.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/js_string.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/math_patch.dart
-FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/mirrors_patch_cfe.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/native_helper.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/regexp_helper.dart
 FILE: ../../../third_party/dart/sdk/lib/_internal/js_runtime/lib/string_helper.dart
@@ -9816,10 +9815,10 @@ FILE: ../../../third_party/dart/sdk/lib/core/null.dart
 FILE: ../../../third_party/dart/sdk/lib/core/stacktrace.dart
 FILE: ../../../third_party/dart/sdk/lib/core/string_sink.dart
 FILE: ../../../third_party/dart/sdk/lib/core/symbol.dart
-FILE: ../../../third_party/dart/sdk/lib/internal/bytes_builder.dart
 FILE: ../../../third_party/dart/sdk/lib/internal/list.dart
 FILE: ../../../third_party/dart/sdk/lib/internal/print.dart
 FILE: ../../../third_party/dart/sdk/lib/internal/symbol.dart
+FILE: ../../../third_party/dart/sdk/lib/io/bytes_builder.dart
 FILE: ../../../third_party/dart/sdk/lib/io/data_transformer.dart
 FILE: ../../../third_party/dart/sdk/lib/io/file.dart
 FILE: ../../../third_party/dart/sdk/lib/io/file_impl.dart