Roll src/third_party/dart fe9f30c..8ad8abf (19 commits) (#14480)

https://dart.googlesource.com/sdk.git/+log/fe9f30c3896e..8ad8abfb7463

git log fe9f30c..8ad8abf --date=short --first-parent --format='%ad %ae %s'
2019-12-13 sigmund@google.com Enable strong/weak strict checking in ddc runtime from the test runner
2019-12-13 rmacnak@google.com [vm, gc] Flatten promotion allocations.
2019-12-13 brianwilkerson@google.com Update the server protocol to not require a port number
2019-12-13 sstrickl@google.com [vm/compiler] During DCE, remove PushArguments of non-live definitions.
2019-12-13 sra@google.com [dart2js] new-rti: Put sourceInformation on more nodes
2019-12-13 sra@google.com [dart2js] avoid empty statement in single-unit output
2019-12-13 brianwilkerson@google.com Add newly reviewed diagnostic docs
2019-12-13 markzipan@google.com [dartdevc] Cleaning up analysis errors.
2019-12-13 johnniwinther@google.com [cfe] Implement nnbd-top-merge
2019-12-13 nshahan@google.com [dartdevc] Remove dead code that handles functions in asserts
2019-12-13 nshahan@google.com [dartdevc] Actually use the libraries from the NNBD fork of the SDK
2019-12-13 srawlins@google.com NNBD Preview is a single-page application.
2019-12-13 zichangguo@google.com Revert "[dart:io] RawSocketOption.fromInt should follow the same endian as host"
2019-12-13 scheglov@google.com Remove DevCompilerResynthesizerBuilder from analyzer.
2019-12-13 kustermann@google.com Reland "[vm/compiler] Fix TypeTestingStub -> SubtypeTestCache fallback code if dst_type = TypeParameter"
2019-12-13 sstrickl@google.com [vm] Weaken dwarf_stack_trace expected stack trace.
2019-12-13 johnniwinther@google.com [cfe] Add weak mode testing
2019-12-13 sigurdm@google.com Bump pub version
2019-12-13 scheglov@google.com Stop supporting _sdkext, look for _embedder.yaml only in sky_engine package.

Created with:
  gclient setdep -r src/third_party/dart@8ad8abfb7463

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

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': 'fe9f30c3896e7146195ea52434c5082b309b6ee0',
+  'dart_revision': '8ad8abfb7463e33e6ac4363437ce843b3ebc7115',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -78,7 +78,7 @@ vars = {
   'dart_pedantic_tag': 'v1.8.0',
   'dart_pool_tag': '1.3.6',
   'dart_protobuf_rev': '3746c8fd3f2b0147623a8e3db89c3ff4330de760',
-  'dart_pub_rev': 'ff5ad1eab1649a8eee6cc593302d3624d9853049',
+  'dart_pub_rev': '4d8ecbd409d773fec47da33b7e6c8db0b51487fd',
   'dart_pub_semver_tag': '1.4.2',
   'dart_quiver-dart_tag': '2.0.0+1',
   'dart_resource_rev': 'f8e37558a1c4f54550aa463b88a6a831e3e33cd6',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 4a9c6b6941eaabf6dfbd9b350ca992a3
+Signature: d13dcfbd5becad76241ebda46d378513
 
 UNUSED LICENSES: