Roll src/third_party/dart be66176534..f4229da6ab (29 commits)

dart-lang/sdk@f4229da6ab [vm, bytecode] Produce compile-time errors instead of crashing when failing to resolve libraries etc.
dart-lang/sdk@a64b06ec83 [gardening] Migrate most files to be implicit-bool-conversion free
dart-lang/sdk@698d120328 base processor migration; fix to add type annotations
dart-lang/sdk@d9a9346c3f [vm/compiler] Fix truncating logic
dart-lang/sdk@d2dc053752 Corrections to "[vm] Fix ASAN build."
dart-lang/sdk@592914fb8b Don't report HintCode.CAN_BE_NULL_AFTER_NULL_AWARE when NNBD.
dart-lang/sdk@c219a76652 Reland "[vm/ffi] Implement FFI callbacks on AOT for ELF and Asm snapshots (excl. blobs)."
dart-lang/sdk@6a8c988fc4 Simplify the computeCompilerArguments().
dart-lang/sdk@9a847a98e8 [ VM / Service ] Fix docs for @Instance not including optional closureFunction and closureContext fields
dart-lang/sdk@ff8b43750a Move reporting INVALID_ASSIGNMENT for compound assignments into StaticTypeAnalyzer.
dart-lang/sdk@cf5e9ca423 Additional tests and fixes for creating getters
dart-lang/sdk@6e3498cd08 bump server SDK constraint lower bound
dart-lang/sdk@89dde0501d Migration: fix handling of assignments involving FutureOr.
dart-lang/sdk@ec48af600f Support fix to import a library defining an extention
dart-lang/sdk@4fbd758f9e [vm/bytecode] Optimize comparisons with null
dart-lang/sdk@16a4c0d13c Bump up oldest_supported_abi_version for abi bot
dart-lang/sdk@c7bb9cf5c4 refactor to share common fix/assist processor code
dart-lang/sdk@5a45050d1e [observatory] Flatten the heap snapshot before loading.
dart-lang/sdk@75374b89f6 [vm] Fix ASAN build.
dart-lang/sdk@8ee3f314cb [vm/gardening] clang tidy fixes
dart-lang/sdk@89ad636b58 Remove the old "preview Dart 2" flags from the test runner.
dart-lang/sdk@aa34de3fe5 Flow analysis: adjust _variableInfosEqual to do a shallow comparison.
dart-lang/sdk@ea35690b96 Flow analysis: add unit tests of try/finally handling.
dart-lang/sdk@b179ef33ec Flow analysis: add unit tests of try/catch handling.
dart-lang/sdk@e2a00dc465 Flow analysis: add unit tests of while statements
dart-lang/sdk@edceedff90 [vm, reload] Allow any change to a class that hasn't yet been declaration loaded.
dart-lang/sdk@68ba13e4e8 With NNBD null-shorting is performed.
dart-lang/sdk@a7723d5c40 [vm] Out-line handle allocation.
dart-lang/sdk@16be3a095d [vm/benchmark] Add *Bytes suffix to Isolate SendReceive benchmark

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': 'be661765345f62fa4212b76f897fdd3e66e8aa54',
+  'dart_revision': 'f4229da6ab73c9041261df658d8b8874689f87fe',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py