Roll src/third_party/dart 8e0a669..8e4dcf4 (8 commits)

8e4dcf4 [vm/compiler/aot] Fix unboxing of int32/uint32 in typed data specializer
287c9de [infra] Update checked in SDKs to 2.2.1-dev.3.1
6d47db7 bump to linter 0.1.85
4ca7401 [co19] Roll to 7e743ef29b4c06f1a2b8b9dc70ead60b31aab526
94baf38 Revert "Revert "set empty environment defines to CompilerOptions""
fadae89 Remove unused imports
2687486 [SDK] Adds .exe extension for Windows binaries in dart_sdk.py.
d75a49a [CFE] Ignore abstract methods when looking for operator '=='.

DEPS

@@ -31,7 +31,7 @@ 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': '8e0a669e746b5a2f4ae07f877b6f754743d8bb97',
+  'dart_revision': '8e4dcf48c4bb64beaf930b3f85f6e4d01b570203',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -60,7 +60,7 @@ vars = {
   'dart_http_throttle_tag': '1.0.2',
   'dart_intl_tag': '0.15.7',
   'dart_json_rpc_2_tag': '2.0.9',
-  'dart_linter_tag': '0.1.84',
+  'dart_linter_tag': '0.1.85',
   'dart_logging_tag': '0.11.3+2',
   'dart_markdown_tag': '2.0.2',
   'dart_matcher_tag': '0.12.3',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: fdee877841854f0765109e4194b4a4c6
+Signature: 0b65326c10b07fe94aff5d5d32b01635
 
 UNUSED LICENSES: