Rolls engine to head with
[fixes](https://github.com/flutter/flutter/pull/127505) corresponding to
the [latest Dart roll](https://github.com/flutter/engine/pull/42286).

https://github.com/flutter/engine/compare/ef5c349f04d8...c784d6d4137d

2023-05-12
[skia-flutter-autoroll@skia.org](mailto:skia-flutter-autoroll@skia.org)
Roll Dart SDK from 7ad028c26344 to 4028c7d8b87c (8 revisions)
(https://github.com/flutter/engine/pull/41967)

Requires some update for changes to the Dart analyzer

fixes https://github.com/flutter/flutter/issues/126683

* match error statements without relying on volatile human readable descriptions

* simplify String list map call