Parser emits compile-time errors on a correct program

[chloestefantsova]

The following program is the repro.

abstract class A {
  void foo() {}
}

class B extends A {
  void bar(bool t) {
    t ? this.foo() : this.foo();
  }
}

The emitted errors are the following:

/tmp/qwerty.dart:7:9: Error: Expected an identifier, but got 'this'.
Try inserting an identifier before 'this'.
    t ? this.foo() : this.foo();
        ^^^^
/tmp/qwerty.dart:7:13: Error: Expected ':' before this.
    t ? this.foo() : this.foo();
            ^
/tmp/qwerty.dart:7:18: Error: Expected ';' after this.
    t ? this.foo() : this.foo();
                 ^
/tmp/qwerty.dart:7:20: Error: Expected an identifier, but got ':'.
Try inserting an identifier before ':'.
    t ? this.foo() : this.foo();
                   ^
/tmp/qwerty.dart:7:20: Error: Unexpected token ';'.
    t ? this.foo() : this.foo();
                   ^