anchor.diff:  
     group('Expression compiler tests in static function:', () {
       const source = '''
  +      // @dart = 2.9
         int foo(int x, {int y}) {
           int z = 0;
           /* evaluation placeholder */
  
positive.code: 
    group('Expression compiler tests in conditional (then):', () {
      const source = r'''
        int globalFunction() {
          int x = 1;
          var c = C(1, 2);
  
negative.code: 
    group('Expression compiler tests in constructor:', () {
      const source = '''
        // @dart = 2.9
        extension NumberParsing on String {
          int parseInt() {
            return int.parse(this);
  