This cleans up the dismissable_test to be less fragile, and make it harder to forget to reset things between runs.

I eliminated a bunch of globals that were susceptible to being missed and passed them in to buildTest instead, and removed some values that were always the same (itemExtent).

Issue 88543: TextField labelText doesn't get hintTextStyle when labelTextStyle is non-null Fixed (#89386)

labelText now gets hintTextStyle when no labelStyle, per the docs

e70febab6 Roll Dart SDK from 4aff633d5ef2 to 1874cf447307 (2 revisions) (flutter/engine#28678) (#90246)

* Create DeltaTextInputClient

* Remove old tests as updateEditingValueWithDeltas is no longer implemented

* fix analyzer

* Update docs

* Make example more general

* Update docs

* Add assert to check that TextInputClient is a DeltaTextInputClient

* Update assert

* More docs

* update

* Clean up docs

* updates

* Update docs

* updates

* Fix test

* add test

* updates

* remove logs

* fix tests

* Address reviewer comments

* Add text_input_utils.dart

* Address reviewer comments

* fixed a small messaging bug

* forgot to remove a s

Improve the layout/sizing of InputDecorator

33f5f17bc Flip on leak detector and suppress or fix remaining leak traces (flutter/engine#28625) (#90222)

* Use the report lines flag

* Handle major version bumps in the version check

* Fix existing tests and add a new test