Fix warnings_checker.dart handling of multitests

tests/language_strong/instanceof4_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 testing the instanceof operation.
 // Regression test for issue 5216.
 // VMOptions=--optimization-counter-threshold=10 --no-use-osr
 
 import "package:expect/expect.dart";
 
 class Foo<T> {
   bool isT() => "a string" is T;
   bool isNotT() => "a string" is! T;
   bool isListT() => [0, 1, 2] is List<T>;
   bool isNotListT() => [0, 1, 2] is! List<T>;
   bool isAlsoListT() => <int>[0, 1, 2] is List<T>;
   bool isNeitherListT() => <int>[0, 1, 2] is! List<T>;
 }
 
 testFooString() {
   var o = new Foo<String>();
   Expect.isTrue(o.isT());
   Expect.isTrue(!o.isNotT());
   Expect.isTrue(o.isListT());
   Expect.isTrue(!o.isNotListT());
-  Expect.isTrue(!o.isAlsoListT()); // /// 01: ok
-  Expect.isTrue(o.isNeitherListT()); // /// 01: ok
+  Expect.isTrue(!o.isAlsoListT()); // //# 01: ok
+  Expect.isTrue(o.isNeitherListT()); // //# 01: ok
   for (var i = 0; i < 20; i++) {
     // Make sure methods are optimized.
     o.isT();
     o.isNotT();
     o.isListT();
     o.isNotListT();
-    o.isAlsoListT(); // /// 01: ok
-    o.isNeitherListT(); // /// 01: ok
+    o.isAlsoListT(); // //# 01: ok
+    o.isNeitherListT(); // //# 01: ok
   }
   Expect.isTrue(o.isT(), "1");
   Expect.isTrue(!o.isNotT(), "2");
   Expect.isTrue(o.isListT(), "3");
   Expect.isTrue(!o.isNotListT(), "4");
-  Expect.isTrue(!o.isAlsoListT(), "5"); // /// 01: ok
-  Expect.isTrue(o.isNeitherListT(), "6"); // /// 01: ok
+  Expect.isTrue(!o.isAlsoListT(), "5"); // //# 01: ok
+  Expect.isTrue(o.isNeitherListT(), "6"); // //# 01: ok
 }
 
 testFooInt() {
   var o = new Foo<int>();
   Expect.isTrue(!o.isT());
   Expect.isTrue(o.isNotT());
   Expect.isTrue(o.isListT());
   Expect.isTrue(!o.isNotListT());
   Expect.isTrue(o.isAlsoListT());
   Expect.isTrue(!o.isNeitherListT());
@@ skipping 11 matching lines @@
   Expect.isTrue(o.isListT());
   Expect.isTrue(!o.isNotListT());
   Expect.isTrue(o.isAlsoListT());
   Expect.isTrue(!o.isNeitherListT());
 }
 
 main() {
   testFooString();
   testFooInt();
 }