Fix warnings_checker.dart handling of multitests

tests/language/constructor_call_as_function_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Dart test program to make sure we catch missing new or const
 // when allocating a new object.
 
 
 class Point {
   const Point(this.x, this.y);
   final int x;
   final int y;
 }
 
 main() {
-  Point p = Point(1, 2); // /// 01: static type warning, runtime error
+  Point p = Point(1, 2); // //# 01: static type warning, runtime error
 }