Roll Dart SDK from 20bf2fcf5670 to cfeb1d647ae5 (22 revisions)

[skia-flutter-autoroll]

https://dart.googlesource.com/sdk.git/+log/20bf2fcf5670..cfeb1d647ae5

2020-07-14 joshualitt@google.com [dart2js] Port some tests to nnbd #5.
2020-07-14 sortie@google.com Roll benchmarks-internal 9bfe209a53a5..ab5ac38ce09a
2020-07-14 sra@google.com [dart2js] Constant-fold some cases of x.toInt()
2020-07-14 joshualitt@google.com [dart2js] Port ~20 tests to nnbd #2.
2020-07-14 alexmarkov@google.com [vm/bytecode] Update Inliner_List_generate unit test in bytecode mode
2020-07-14 alexmarkov@google.com [vm/aot/nnbd] Avoid deduplicating mixins with different NNBD modes
2020-07-14 danny@tuppeny.com Add dart.lineLength setting to the LSP docs
2020-07-14 scheglov@google.com Remove FolderBasedDartSdk.defaultSdkDirectory() and getSdkProperty().
2020-07-14 jakemac@google.com update charcode in the sdk to the nnbd version
2020-07-14 brianwilkerson@google.com Update the wrap-in-padding fix to not add the keyword const when in a constant context
2020-07-14 fmil@google.com Fix the #include path for ICU headers
2020-07-14 scheglov@google.com Stop using FormalParameter.kind in analyzer.
2020-07-14 sortie@google.com [benchmark] Use the VM from the SDK for analyzer benchmarks.
2020-07-14 paulberry@google.com Make "ID" tests insensitive to what directory they're run from.
2020-07-14 kustermann@google.com [infra] Add using_goma=False (fixes recent tools/build.py change)
2020-07-14 scheglov@google.com Stop supporting 'target?.[index]' and QUESTION_PERIOD_OPEN_SQUARE_BRACKET.
2020-07-14 dmitryas@google.com [cfe] Eliminate UnknownType in async type downcasts
2020-07-14 kustermann@google.com [infra] Prepare to make tools/build.py always re-runs GN.
2020-07-14 johnniwinther@google.com [cfe] Update expectations after sdk change
2020-07-14 johnniwinther@google.com [cfe] Add support for keeping const locals during constant evaluation
2020-07-14 johnniwinther@google.com [cfe] Ensure legacy result types for invocation and access in opt-out libraries
2020-07-14 lrn@google.com Update ListMixin/ListBase documentation and insert for Null Safety.

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/+doc/master/autoroll/README.md