[dart] Roll dart to b99bcfd (flutter#6491)

* [dart] Roll dart to b99bcfd

Changes since last roll:
```
b99bcfd [vm] Add a library and class cache to KernelProgramInfo
5deb1c6 [vm] Remove strong mode and sync-async flags from pkg/vm
9a6f811 Report null error as a NoSuchMethodError
2da0b9f fix some typos
34f6aea [release] Prepare changelog for 2.1.0-dev.7.0
f320477 [dartdevc] add module-name option to kernel backend
b8760fe [vm, compiler] Remove ASTs and AST flow graph builder.
340e746 Clean up OverrideVerifier.
f11e746 Initial implementation of fixes for type arguments on named constructor invocations
08e485c Update dartdoc to 0.23.1.
ac4b8a7 Hook up FixProcessor to fix errors in dartfix
0aa99cc Ignore JSON exceptions when reading (empty) test results file
6d9cc6f Add skeleton for parsing LSP spec from Markdown/TypeScript to generate Dart data classes
bc4d2f5 Switch InheritanceManager2Test to DriverResolutionTest.
e221a62 Move reporting MISMATCHED_GETTER_AND_SETTER_TYPES for classes to using new interfaces.
be39eac Rename convertPathForImport -> convertAbsolutePathToUri
a539d2e Revert "[fasta] Report errors for bounds violations"
c8b709d Update status files after aa6fb2d
051108c [tools] Re-enable core-dump archiving on Linux.
aa5b1b1 Make test results in json format end with a newline
4db2bbe Pass SharedOptions to Fasta
f1d902f Ignore --supermixin and -D options
a9b47bd Integrated nosuchmethod-forwarding.md into dartLangSpec.tex
327a1a9 [Gardening] Mark more co19_2 test as always flaky, filed co19 issues
f1b6d81 Remove Target.strongMode
7072d3b [infra] Upgrade d8 to 6.9.427.23 (flutter#34698)
16ddfc1 [VM] Use assert assignable implementation for explicit downcasts
17ac151 [Gardening] Increase timeout on release-hotreload configuration as well (not just debug), skip streamed_conversion_json_utf8_decode in hot-reload-simdbc64
8c872e0 Remove TargetFlags.strongMode
ee97806 Replace strongMode with legacyMode in CompilerOptions
aa6fb2d [fasta] Report errors for bounds violations
8247fb7 Stop stripping d8 for benchmarking.
da48c1d [Gardening] Mark more tests as flaky and filed co19 issues
41866e8 [Gardening] Mark co19_2 test as always flaky, filed co19 issue (and co19 PR)
ecd13de [Gardening] Mark slow_path_shared_stub_test as slow (reaches 1 minute on windows)
f942af4 Remove kernel interpreter
7007567 Fix issue with --unsafe-package-serialization
2695f36 [Gardening] Status update (co19_2, optcounter/ia32)
ba5e14b Store return type and parameters separately in GenericFunctionTypeElementForLink.
ba1b30a Add AST support for type arguments on named constructors
ed6c557 Add cli parameters to kernel_sdk.dart to get all paths explicitly
71395df [vm/interpreter] Fix flaky errors when running with interpreter
b3af151 Rework detection of uninstantiated bound errors.
34651d2 [gardening] Update status
f35465d Remove DynamicElementImpl.library property.
daa13ad Fix preamble/d8.js currentScript for v8 6.9
9cde31b Try interface candidates in reverse order.
5561e69 Replace dartfix confirm apply changes with --force
619a063 Update dartfix to only allow target directories
751cf19 [dart/fuzzer] Add DBC as execution mode.
7031747 [gardening] Update status
8fc8003 Fix cast exception in OpTypeAstVisitor
2cf6ba2 Generate the right error message for type arguments on a named constructor
5976fe3 Fix up InferredTypeTest_Driver to use InferredTypeMixin directly.
32c484b [VM] Fix typo in BitTestImmediate unit test.
a8e0db1 [gardening] Mark remaining ASAN failures.
7f55e52 [vm, x64] Use short forms for object pool loads.
a66cae4 [vm/aot] Dynamic invocation forwarders in AOT.
4400df4 Convert strong_mode_test.dart to triple-slash comment style.
c136196 Update status files for tests failing due to flutter#34724 and flutter#34724
0039aff [test] Remove use of --error_on_bad_type and --error_on_bad_override.
ce08911 [vm/compiler] Minor improvements to loop detection
a2cf88b [vm] Fix sync-async stack navigation to handle inlined functions.
920d75f Cleanup dartfix driver context
7460347 Update dartfix to separate targets from analysis roots
3d06427 Fix MOVE_FILE test paths for Windows
```

* Remove use of await_is_keyword flag.

* Update license

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': 'a50dfd66980ed5c9aef9851fcc57557fb607769c',
+  'dart_revision': 'b99bcfd3099f0d32e39287160a9539e878cb0b68',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -49,7 +49,7 @@ vars = {
   'dart_csslib_tag': '0.14.4+1',
   'dart_dart2js_info_tag': '0.5.6+4',
   'dart_dart_style_tag': '1.2.0',
-  'dart_dartdoc_tag': 'v0.23.0',
+  'dart_dartdoc_tag': 'v0.23.1',
   'dart_fixnum_tag': '0.10.8',
   'dart_glob_tag': '1.1.7',
   'dart_html_tag': '0.13.3+2',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: aa13b5ea6163edf199855b7adb02bbdc
+Signature: ac08e09569da6bc35a213e80f4f97427
 
 UNUSED LICENSES:
 

lib/snapshot/BUILD.gn

@@ -57,7 +57,6 @@ compiled_action("generate_snapshot_bin") {
     "--sync-async",
     "--reify-generic-functions",
     "--snapshot_kind=core",
-    "--await_is_keyword",
     "--enable_mirrors=false",
     "--vm_snapshot_data=" + rebase_path(vm_snapshot_data),
     "--vm_snapshot_instructions=" + rebase_path(vm_snapshot_instructions),
@@ -196,7 +195,6 @@ compile_platform("strong_platform") {
 
   args = [
     "--target=flutter",
-    "--strong",
     "dart:core",
   ]
 }