* apply upcoming lint cast_nullable_to_non_nullable

* make RenderObjectElement.renderObject non-nullable

This message is displayed if we do not find a pubspec.yaml

99% of the time this additional advice is going to have nothing to do with the actual error. Just remove it because it will cause more confusion than it could clear up

Crash reporting shows at least one instance of EACCES during an existsSync cache call. Add this to the list of error handling io methods. Did not add the async exists method since we lint against its usage.

[Icons][iOS] Pointing to version of material icon font that includes more metadata in the xml. (#66684)

Simple docs fix for characters.

Teach the flutter tool how to find android output files if the flavor contains uppercase letters (#66687)

This changes the name of the generated output files on android in case a flavor with uppercase letters is used.
Previously, the lowercased flavor name would be used for the apk/aab file. Now, the flavor name is used as-is.

The lack of current directory wrapping was letting some of the already handled errors through

Fixes #66675

This PR also enables firebase tests on presubmit and removes code that
won't be used anymore from test runner.

Bug:
  https://github.com/flutter/infra/pull/225

The Dart SDK now requires non-null enum values if the enum is used in an
exhaustive switch statement on a non-nullable type.

See https://github.com/flutter/flutter/issues/66674

This reverts commit 2ae09caa.

This shouldn't break our tests as
https://github.com/flutter/gallery/issues/275 is closed.

* Remove opacity from check and add test

ensure that the terminal handler checks if the service protocol is enabled before calling debug toggle brightness. Also removes globals from TerminalHander and test cases.

Fixes #65477

This reverts commit 48ce83a8.

* b49de93b3 Create an ImageHandle wrapper (flutter/engine#21057)

* b0fb2c8a9 Roll Skia from 7b97b3cb2bd0 to 59b2a92c96ba (4 revisions) (flutter/engine#21365)

Otherwise the heuristics we have may decide to skip running pub. We should consider reducing the number of dimensions of caching here to a single check optimized for the run/test case.

* [Docs] [Icons] Updating dart doc styles to recognize more styles of icons. All the 4 icon styles we support have to be pulled from 4 individual web fonts when we show the html page for api docs.

* Better documentation and that special awful case.

* Couple more places to remove.

Complete the migration to the TextSelectionTheme by deprecating the opt-in flag and text selection properties in ThemeData. (#66482)

* Fixes typos in showDialog documentation