anchor.diff:            prefixes.add(prefix);
           }
         }
  -      _prefixes = prefixes.toList();
  +      _prefixes = prefixes.toList(growable: false);
       }
       return _prefixes;
     }
  
positive.code:       ResynthesizerContext context = enclosingUnit.resynthesizerContext;
        _interfaces = _unlinkedClass.interfaces
            .map((EntityRef t) => context.resolveTypeRef(t, this))
            .toList();
      }
      return _interfaces ?? const <InterfaceType>[];
    }
  
negative.code:       implicitConstructor.enclosingElement = this;
        implicitConstructor.type = new FunctionTypeImpl(implicitConstructor);
        return implicitConstructor;
      }).toList(growable: false);
    }
  
    PropertyAccessorElement _internalLookUpConcreteGetter(
  