Fix warnings_checker.dart handling of multitests

tests/language_strong/cast_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.
 // Dart test program for constructors and initializers.
 
 import "package:expect/expect.dart";
 
 // Test 'expression as Type' casts.
 
 class C {
@@ skipping 17 matching lines @@
   Object on = getNull();
   Object ol = createList();
   Object oi = createInt();
   Object os = createString();
 
   Expect.equals(42, (oc as C).foo);
   Expect.equals(42, (od as C).foo);
   Expect.equals(42, (od as D).foo);
   Expect.equals(37, (od as D).bar);
   Expect.equals(37, ((od as C) as D).bar);
-  (oc as D).foo; // /// 01: runtime error
+  (oc as D).foo; // //# 01: runtime error
   (on as D).toString();
-  (on as D).foo; // /// 02: runtime error
-  (on as C).foo; // /// 03: runtime error
-  oc.foo; // /// 04: static type warning
-  od.foo; // /// 05: static type warning
+  (on as D).foo; // //# 02: runtime error
+  (on as C).foo; // //# 03: runtime error
+  oc.foo; // //# 04: static type warning
+  od.foo; // //# 05: static type warning
   (on as Object).toString();
   (oc as Object).toString();
   (od as Object).toString();
   (on as dynamic).toString();
-  (on as dynamic).foo; // /// 07: runtime error
+  (on as dynamic).foo; // //# 07: runtime error
   (oc as dynamic).foo;
   (od as dynamic).foo;
-  (oc as dynamic).bar; // /// 08: runtime error
+  (oc as dynamic).bar; // //# 08: runtime error
   (od as dynamic).bar;
   C c = oc as C;
   c = od as C;
   c = oc;
   D d = od as D;
-  d = oc as D; // /// 10: runtime error
+  d = oc as D; // //# 10: runtime error
   d = od;
 
   (ol as List)[0];
   (ol as List<int>)[0];
   (ol as dynamic)[0];
-  (ol as String).length; // /// 12: runtime error
+  (ol as String).length; // //# 12: runtime error
   int x = (ol as List<int>)[0];
   (ol as List<int>)[0] = (oi as int);
 
   (os as String).length;
   (os as dynamic).length;
-  (oi as String).length; // /// 13: runtime error
-  (os as List).length; // /// 14: runtime error
+  (oi as String).length; // //# 13: runtime error
+  (os as List).length; // //# 14: runtime error
 
   (oi as int) + 2;
-  (oi as List).length; // /// 15: runtime error
+  (oi as List).length; // //# 15: runtime error
 }