Change CodeAfterTryIsExecutedNegativeTest to a multitest.

dart/tests/language/src/CodeAfterTryIsExecutedTest.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.
+// Test that the runtime still runs the code after a try/catch. The
+// test cannot use Expect.throws, because Expect.throws uses the same
+// pattern.
 
 main() {
   var exception;
   try {
     throw 'foo';
   } catch (String ex) {
     exception = ex;
   }
   Expect.isTrue(exception is String);
-  throw 'foo';
+  throw 'foo'; /// 01: runtime error
 }