* update for the latest Dart SDK roll
* Update DEPS
update the dart revision to 204b67e5a029de64899154068cf1099b4f7db1f1
* Update license hash
Co-authored-by: Alexander Aprelev <aam@google.com>
The charcode package has been removed from the Dart SDK source
checkout, and the Flutter engine packages that list it in
their pubspecs do not depend on it directly or indirectly.
Remove it from their pubspecs, so they do not break when
the package disappears from the engine source checkout.
Bug: https://dart-review.googlesource.com/c/sdk/+/247500
