`redirectedConstructor` apparently changed behavior, is that intended?

[eernstg]

Cf. https://dart-review.googlesource.com/c/sdk/+/139800, which adds the following new test to 'pkg/analyzer/test/generated/parser_test.dart':

  void test_parseClassMember_redirectingGenerativeConstructor() {
    createParser('C.redirecting(): this();');
    var constructor = parser.parseClassMember('C') as ConstructorDeclaration;
    assertNoErrors();
    expect(constructor, isNotNull);
    expect(constructor.externalKeyword, isNull);
    expect(constructor.constKeyword, isNull);
    expect(constructor.factoryKeyword, isNull);
    expect(constructor.returnType.name, 'C');
    expect(constructor.period.type, TokenType.PERIOD);
    expect(constructor.name.name, 'redirecting');
    _assertIsDeclarationName(constructor.returnType, false);
    expect(constructor.parameters, isNotNull);
    expect(constructor.parameters.parameters, isEmpty);
    expect(constructor.separator.type, TokenType.COLON);
    expect(constructor.initializers, hasLength(1));
    ConstructorInitializer initializer = constructor.initializers[0];
    expect(initializer is RedirectingConstructorInvocation, isTrue);
    expect(constructor.redirectedConstructor, isNotNull); // FAILS.
    // expect(constructor.redirectedConstructor.type.name.name, '???');
    // expect(constructor.redirectedConstructor.period, isNull);
    expect(constructor.body, isEmptyFunctionBody);
  }

The interesting part is at the line with the comment // FAILS.. This shows that the redirectedConstructor is null. This behavior is new (it caused a 'reflectable' test to start failing), and it seems likely that it is a bug.

In particular, the redirectedConstructor is also null when the constructor declaration uses this.name(), and this makes it impossible to make the distinction between redirection to different constructors, at least via redirectedConstructor.

The failure in the CFE and in the analyzer can be reproduced locally as follows:

> python tools/test.py -n cfe-unittest-asserts-release-linux pkg/analyzer/test/generated/parser_fasta_test
> python tools/test.py -n analyzer-unittest-asserts-release-linux pkg/analyzer/test/generated/parser_fasta_test

I have chosen 'area-front-end' for this because the issue arises during parsing in both configurations, and because the analyzer uses the front end parser to some extent.