* fix deprecated_new_in_comment_reference for `material` library

in a future version of the SDK, these will be flagged, fix them now

* Update pubspec.yaml

* first pass

* x

* x

* address feedback

* support multiple extensions

* add convenience function, Object ⇒ dynamic, lerping

* remove not-useful comment

* fix examples/api lower sdk constraint

* remove trailing spaces

* remove another pesky trailing space

* improve lerp

* address feedback

* hide map implementation from constructor and copyWith

* use iterableproperty

* Revert "hide map implementation from constructor and copyWith"

This reverts commit a6994af0046e3c90dbc9405cac628feb5b2d3031.

* slow down sample

* make theme extension params required

* add null check

* improve documentation

* fix hashCode and operator == overrides

* modify existing tests

* remove trailing spaces

* add all tests except lerping

* fix lerping bug

* add toString to themeExtension example

* add lerping test

* assume non-nullability in example

* address feedback

* update docs

* remove trailing space

* use Map.unmodifiable

* 0522e8f19 Roll Skia from 3562b565fda0 to b3275e1fd64c (1 revision) (flutter/engine#32129)

* 8ba36276e Roll Dart SDK from 398ee66637cf to c1145b4c0330 (1 revision) (flutter/engine#32130)

* 6b6a68ef7 Roll Fuchsia Linux SDK from uawdfLUeA... to voPt0GIuh... (flutter/engine#32115)

* 79c87aa34 Roll Skia from 1df1a80ad20d to 42bc49d5d332 (3 revisions) (flutter/engine#32116)

* 04bac31cc Roll Skia from 42bc49d5d332 to 35275b3d511f (5 revisions) (flutter/engine#32119)

* 6a877cab6 allow experimentally opting into MSAA on canvaskit (flutter/engine#32045)

* 3edd312b9 Add deps to builder `web_engine_framework` (flutter/engine#32112)

* 641af02c4 [macOS TextInputPlugin] Reactivate input context on key event (flutter/engine#32117)

* 63e715bba Roll Skia from 35275b3d511f to b8c117ced234 (2 revisions) (flutter/engine#32125)

* 600ae5af9 Modify some tests to work correctly on iOS 15. (flutter/engine#32124)

* Add fadeDuration back to TextSelectionOverlay

* fix build and add dart fix

* format

* add test