dart format support for records

[dcharkes]

$ dart analyze --enable-experiment=records record.dart
Analyzing record.dart...               0.4s
No issues found!

$ dart format --enable-experiment=records record.dart
Could not find an option named "enable-experiment".

$ dart --enable-experiment=records format record.dart
# and
$ dart format record.dart
# choke on record types.

Snippet that causes issues:

final returnStruct3BytesHomogeneousUint8VariadicLeaf =
    ffiTestFunctions.lookupFunction<
        Struct3BytesHomogeneousUint8 Function(Uint8, VarArgs<(Uint8, Uint8)>),
        Struct3BytesHomogeneousUint8 Function(int, int,
              int)>("ReturnStruct3BytesHomogeneousUint8Variadic", isLeaf: true);

@munificent

[munificent]

Duplicate of dart-lang/dart_style#1128.