anchor.diff:      if (actualBody != null) {
         unexpected("null", "${actualBody.runtimeType}", charOffset, fileUri);
       }
  -    actualBody = new RedirectingFactoryBody(target);
  +    actualBody = new RedirectingFactoryBody(target, typeArguments);
       function.body = actualBody;
       actualBody?.parent = function;
       if (isPatch) {
  
positive.code:     function.body = actualBody;
      actualBody?.parent = function;
      if (isPatch) {
        actualOrigin.setRedirectingFactoryBody(target, typeArguments);
      }
    }
  
negative.code:         StringLiteral,
          SuperInitializer,
          TypeParameter,
          TypeParameterType,
          VariableDeclaration,
          VariableGet,
          VoidType,
  