Fix warnings_checker.dart handling of multitests

tests/language_strong/try_catch4_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.
 // Check that our SSA graph does have the try body a predecessor of a
 // try/finally.
 // VMOptions=--optimization-counter-threshold=10
 
 import "package:expect/expect.dart";
 
 var a;
 
 foo1() {
   var b = false;
   var entered = false;
   while (true) {
-    if (entered) return b; /// static warning
+    if (entered) return b; //# static warning
     b = 8 == a; // This expression should not be GVN'ed.
     try {
       a = 8;
-      return; /// static warning
+      return; //# static warning
     } finally {
       b = 8 == a;
       entered = true;
       continue;
     }
   }
 }
 
 doThrow() { throw 2; }
 
 foo2() {
   var b = false;
   var entered = false;
   while (true) {
-    if (entered) return b; /// static warning
+    if (entered) return b; //# static warning
     b = 8 == a; // This expression should not be GVN'ed.
     try {
       a = 8;
       doThrow();
-      return; /// static warning
+      return; //# static warning
     } catch(e) {
       b = 8 == a;
       entered = true;
       continue;
     }
   }
 }
 
 foo3() {
   var b = false;
   var entered = false;
   while (true) {
-    if (entered) return b; /// static warning
+    if (entered) return b; //# static warning
     b = 8 == a; // This expression should not be GVN'ed.
     try {
       doThrow();
     } catch(e) {
       a = 8;
       entered = true;
-      return; /// static warning
+      return; //# static warning
     } finally {
       b = 8 == a;
       entered = true;
       continue;
     }
   }
 }
 
 foo4() {
   var b = false;
@@ skipping 124 matching lines @@
   Expect.isTrue(foo8());
   a = 0;
   Expect.isTrue(foo9());
 }
 
 main() {
   for (var i = 0; i < 20; i++) {
     main_test();
   }
 }