Fix warnings_checker.dart handling of multitests

tests/language/dynamic_field_test.dart

 // Copyright (c) 2012, 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.
 //
 // Test that ensures that fields can be accessed dynamically.
 
 import "package:expect/expect.dart";
 
 class A extends C {
   var a;
   var b;
 }
 
 class C {
   foo() {
-    print(a); /// 01: static type warning
-    return a; /// 01: continued
+    print(a); //# 01: static type warning
+    return a; //# 01: continued
   }
   bar() {
-    print(b.a); /// 02: static type warning
-    return b.a; /// 02: continued
+    print(b.a); //# 02: static type warning
+    return b.a; //# 02: continued
   }
 }
 
 main() {
   var a = new A();
   a.a = 1;
   a.b = a;
-  Expect.equals(1, a.foo()); /// 01: continued
-  Expect.equals(1, a.bar()); /// 02: continued
+  Expect.equals(1, a.foo()); //# 01: continued
+  Expect.equals(1, a.bar()); //# 02: continued
 }