Optimize functions containing try-catch.

tests/language/try_catch5_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.
 
 import "package:expect/expect.dart";
 
 var a;
 
@@ skipping 12 matching lines @@
         entered = true;
         continue;
       }
     } finally {
       continue;
     }
   }
 }
 
 main() {
-  a = 0;
-  Expect.isTrue(foo1());
+  for (var i = 0; i < 2000; i++) {
+    a = 0;
+    Expect.isTrue(foo1());
+  }
 }