Fix warnings_checker.dart handling of multitests

tests/language/switch_bad_case_test.dart

 // Copyright (c) 2013, 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 reporting a compile-time error if case expressions do not all have
 // the same type or are of type double.
 
 import "package:expect/expect.dart";
 
 void main() {
   Expect.equals("IV", caesarSays(4));
   Expect.equals(null, caesarSays(2));
   Expect.equals(null, archimedesSays(3.14));
 }
 
 caesarSays(n) {
   switch (n) {
     case 1:
       return "I";
     case 4:
       return "IV";
-    case "M": //        /// 01: compile-time error
-      return 1000; //   /// 01: continued
+    case "M": //        //# 01: compile-time error
+      return 1000; //   //# 01: continued
   }
   return null;
 }
 
 archimedesSays(n) {
-  switch (n) { //       /// 02: continued
-    case 3.14: //       /// 02: compile-time error
-      return "Pi"; //   /// 02: continued
-    case 2.71828: //    /// 02: continued
-      return "Huh?"; // /// 02: continued
-  } //                  /// 02: continued
+  switch (n) { //       //# 02: continued
+    case 3.14: //       //# 02: compile-time error
+      return "Pi"; //   //# 02: continued
+    case 2.71828: //    //# 02: continued
+      return "Huh?"; // //# 02: continued
+  } //                  //# 02: continued
   return null;
 }