Fix warnings_checker.dart handling of multitests

tests/language/call_nonexistent_constructor_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.
 
 import "package:expect/expect.dart";
 
 // When attempting to call a nonexistent constructor, check that a
 // NoSuchMethodError is thrown.
 
 foo() {
   throw 'hest';
 }
 
 class A {
   A.foo(var x) {}
 }
 
 main() {
   int i = 0;
   new A.foo(42);
   try {
     // Args are evaluated before throwing NoSuchMethodError:
-    new A.bar(foo()); /// 01: static type warning
+    new A.bar(foo()); //# 01: static type warning
   } on NoSuchMethodError catch (e) {
     i = -1;
   } on String catch (e) {
     i = 1;
   }
-  Expect.equals(1, i); /// 01: continued
+  Expect.equals(1, i); //# 01: continued
   try {
-    new A(); /// 02: static type warning
+    new A(); //# 02: static type warning
   } on NoSuchMethodError catch (e) {
     i = 2;
   }
-  Expect.equals(2, i); /// 02: continued
+  Expect.equals(2, i); //# 02: continued
 }