The rules for returns with null-safety were changed in language PR #941,
and this PR makes changes to async/return_types_test.dart such that it
matches the new rules. Check base vs. patchset 1 to see these adjustments.

The main part of this PR is that it migrates and updates the tests
language/invalid_returns/{,a}sync_{,in}valid*_test.dart such
that they match the new rules. Check patchset 1 vs newest patchset
to see this migration.

Note that some tests are new, e.g., 'sync_invalid_return_27_test',
which was added because it is a new property that there is an error
for "return void to Null". Also note that some of the tests are
redundant: (1) It is no longer allowed to return void to Null, but
(2) that's an error already with null-safety, because it's a
downcast (so it doesn't matter which supertype of `Null` we have).
I kept these tests anyway (and even wrote this new one), because
they do check that certain changes have been implemented, even
though it is in some cases redundant in the sense that it's just
another verification that implicit downcasts aren't supported any
more. If we don't want this redundancy then we should remove about
10 tests (sync_invalid_return, async_invalid_return).

Change-Id: I3f10682e1d0ed75067d6e8651588b727ffd3648f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/145587
Commit-Queue: Erik Ernst <eernst@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>

…buf, shelf, test, tools, vector_math, webdev

Revisions updated by `dart tools/rev_sdk_deps.dart`.

dartdoc (https://github.com/dart-lang/dartdoc/compare/59dc475..1d94484):
  1d94484c  2023-05-29  dependabot[bot]  Bump github/codeql-action from 2.3.3 to 2.3.5 (#3422)
  0edc1a71  2023-05-28  dependabot[bot]  Bump http from 0.13.6 to 1.0.0 (#3421)

http (https://github.com/dart-lang/http/compare/dfec389..8a4a4a6):
  8a4a4a6  2023-05-25  Brian Quinlan  Add a better toString to _ClientSocketException (#948)
  5c1f1ad  2023-05-25  Devon Carew  regenerate with the latest mono_repo (#947)

leak_tracker (https://github.com/dart-lang/leak_tracker/compare/9c6e9b3..7f2cab3):
  7f2cab3  2023-05-26  Polina Cherkasova  Nicely format retaining path. (#68)

lints (https://github.com/dart-lang/lints/compare/72f107a..4236c43):
  4236c43  2023-05-26  Parker Lougheed  Remove pedantic from README (#124)
  4ac79d8  2023-05-24  Parker Lougheed  Update example for latest lints version (#123)

mockito (https://github.com/dart-lang/mockito/compare/153c145..40fe2ca):
  40fe2ca  2023-05-25  Nate Bosch  Expand constraint on package:http

native (https://github.com/dart-lang/native/compare/45e16dc..76bc55e):
  76bc55e  2023-05-30  Daco Harkes  [c_compiler] Target ios_x64 (#53)

protobuf (https://github.com/dart-lang/protobuf/compare/7d2d293..346a72d):
  346a72d  2023-05-30  Ömer Sinan Ağacan  Fix generated ignore_for_file directives (#833)
  35ea45f  2023-05-26  Kevin Moore  Latest mono_repo (#834)

shelf (https://github.com/dart-lang/shelf/compare/56919a1..a404b6a):
  a404b6a  2023-05-25  Devon Carew  re-generate w/ the latest monorepo (#362)

test (https://github.com/dart-lang/test/compare/309596e..3276921):
  32769215  2023-05-25  dependabot[bot]  Bump github/codeql-action from 2.3.2 to 2.3.5 (#2023)
  f74e85c8  2023-05-25  dependabot[bot]  Bump dart-lang/setup-dart from 1.3.0 to 1.5.0 (#2022)
  4b2bd272  2023-05-25  Devon Carew  update the mono_repo and dependabot configs (#2021)

tools (https://github.com/dart-lang/tools/compare/81ff996..b90a7e8):
  b90a7e8  2023-05-26  Devon Carew  blast_repo fixes (#106)

vector_math (https://github.com/google/vector_math.dart/compare/e3de8da..cd87f57):
  cd87f57  2023-05-30  JKris95  Axis calculation of quaternions from small angles (#272)
  3762b25  2023-05-30  Lukas Klingsbo  Removes the `new` keyword from readme (#284)
  df5877f  2023-05-30  Lukas Klingsbo  Use named constructors in Vector2 and some general optimizations (#289)

webdev (https://github.com/dart-lang/webdev/compare/d74fadd..4b69f1d):
  4b69f1dd  2023-05-26  Anna Gringauze  fix format breaking tests (#2124)
  b75f8e62  2023-05-25  Devon Carew  re-generate w/ the latest monorepo (#2121)

Change-Id: Ide9b7781102b654db15114d01cd4fbca40478906
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/306304
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Devon Carew <devoncarew@google.com>