dart linter
https://pub.dev/packages/lint and https://pub.dev/packages/linter depends on `dart analyze` which only works on an entire project.

https://github.com/dart-lang/dart_style runs standalone on files provided on the CLI.

And it identifies these fixes
```
diff --git a/tests/expected/coverage.dart b/tests/expected/coverage.dart
index b606b1b..a791231 100644
--- a/tests/expected/coverage.dart
+++ b/tests/expected/coverage.dart
@@ -30,7 +30,7 @@ show() {
   print(sprintf("%s", [a5.length]));
   List<String> a9 = ["a", "b", "c", "d"];
   print(sprintf("%s", [a9.length]));
-  final Set<int> a6 = new Set.from([1, 2, 3, 4]);
+  final Set<int> a6 = Set.from([1, 2, 3, 4]);
   print(sprintf("%s", [a6.length]));
   final Map<String, int> a7 = {"a": 1, "b": 2};
   print(sprintf("%s", [a7.length]));
diff --git a/tests/expected/global2.dart b/tests/expected/global2.dart
index 3fc057b..a68f925 100644
--- a/tests/expected/global2.dart
+++ b/tests/expected/global2.dart
@@ -5,7 +5,7 @@ final int code_0 = 0;
 final int code_1 = 1;
 final String code_a = "a";
 final String code_b = "b";
-final Set<String> l_b = new Set.from([code_a]);
+final Set<String> l_b = Set.from([code_a]);
 final Map<String, int> l_c = {code_b: code_0};
 main() {
   assert(l_b.contains("a"));
```