Dart should compile with -Wnewline-eof to match Flutter

[eseidel]

When Flutter compiles Dart it uses -Wnewline-eof, supposedly to match fuchsia:
https://github.com/flutter/flutter/blob/8893670e159698ae57307bf72922f1f1c8ee7d48/engine/src/build/config/clang/BUILD.gn#L22

Dart doesn't use this flag (understandably), but it makes it so when you add a file in Dart you risk only realizing you're going to break the build in Flutter when you roll, rather than when you add the file.

For Shorebird we've fixed this by adding this flag, but I'm not sure I've done it in the right place. Will send a PR shortly.

[rmacnak-google]

https://dart-review.googlesource.com/c/sdk/+/417863

[eseidel]

Ah, I guess when things land through gerrit they aren't automagically closed by "fixes X" like landing through GitHub does.

Thanks!

[FMorschel]

Exactly, @eseidel . I have opened dart-lang/dart_ci#166 about this but no feedback yet.