Fix warnings_checker.dart handling of multitests

tests/language/mixin_invalid_bound_test.dart

 // Copyright (c) 2014, 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.
 
 class S0<T> { }
 
 class S<T extends num> extends S0<String> { }
 
 class M<T extends num> { }
 
 class A<T extends num> extends S with M { }
 
 // A StaticWarning is reported here and in C, D, and E below, because T is not
 // bounded. The purpose of this test is to verify bound checking in S, M, and A,
 // the reason no bound is declared for T here.
 class B<T> extends S<T> with M<int> { }
 
 class C<T> extends S<int> with M<T> { }
 
 class D<T> extends S<T> with M<bool> { }
 
 class E<T> extends S<bool> with M<T> { }
 
 main() {
-  new A<int>(); // /// 01: static type warning
-  new A<bool>(); // /// 02: static type warning, dynamic type error
-  new B<int>(); // /// 03: static type warning
-  new B<bool>(); // /// 04: static type warning, dynamic type error
-  new C<int>(); // /// 05: static type warning
-  new C<bool>(); // /// 06: static type warning, dynamic type error
-  new D<int>(); // /// 07: static type warning, dynamic type error
-  new D<bool>(); // /// 08: static type warning, dynamic type error
-  new E<int>(); // /// 09: static type warning, dynamic type error
-  new E<bool>(); // /// 10: static type warning, dynamic type error
+  new A<int>(); // //# 01: static type warning
+  new A<bool>(); // //# 02: static type warning, dynamic type error
+  new B<int>(); // //# 03: static type warning
+  new B<bool>(); // //# 04: static type warning, dynamic type error
+  new C<int>(); // //# 05: static type warning
+  new C<bool>(); // //# 06: static type warning, dynamic type error
+  new D<int>(); // //# 07: static type warning, dynamic type error
+  new D<bool>(); // //# 08: static type warning, dynamic type error
+  new E<int>(); // //# 09: static type warning, dynamic type error
+  new E<bool>(); // //# 10: static type warning, dynamic type error
 }