Now that https://github.com/dart-lang/sdk/issues/41985 is fixed, the
analyzer detects dead code due to "unnecessary" null checks.  Since we
want to retain null checks in Flutter even when they appear
unnecessary (in order to preserve runtime behavior in weak mode), we
need to suppress these dead code hints.

Note that one assertion is removed by this PR (`heightFactor != null
|| (heightFactor == 1.0 && heightDelta == 0.0)`).  This is because
`heightFactor == 1.0 && heightDelta == 0.0` can only be true if
`heightFactor != null`, so this assertion is equivalent to simply
asserting that `heightFactor != null`, which is already asserted two
lines above.

* add enabled flag

* remove flaky flag for try builders

* remove trailing space

* migrate painting to nullsafety

* address review comments

* Remove hostonly_tests from cirrus as they are now running on LUCI.

Bug:
  https://github.com/flutter/flutter/issues/63242

* Remove templates add framework tests for linux back.

* Fix sort indicator for DataTables

As per material spec ascending order should be shown via an upward arrow
This commit changes the displayed arrows accordingly.

* Test sort indicator orientation in DataTable

These widgets are missing from
https://github.com/flutter/flutter/pull/59364

With this change, developers can use clipBehavior for
https://github.com/flutter/flutter/issues/59424

Remove globals and testbed to simplify test cases, using the existing environment configuration. This is some pre-factoring work to make landing #63610 easier

This reverts commit c67eafa8.

* Add native stacktrace field for PlatformException

* Mute the readValue check for stacktrace.

* polish

* Add unit test and further polish

* Added more comments

* remove unnecessary import

* fill in stacktrace to JSONMethodCodec and fix tests

* fix style

* Fix format

* Remove unnecessary TODO since not all explicitly declared errors have stacktrace in it from native side.

* Handle case for exception without stacktrace on jsonMethodCodec

* Add more unit tests

* format test
Co-authored-by: Ben Li <libe@google.com>

Revert: Update prepare_package.dart to use the process_runner package instead having duplicate code. #62710 (#63608)

This reverts #62710, since it has a noSuchMethodError in some circumstances.

This isn't just a straight git revert, because I had to resolve the conflicts in the reverted pubspec.yaml files and re-run flutter update-packages --force-upgrade to make the checksums match.