Switch-implementation.

frog/leg/lib/js_helper.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.
 
 #library('js_helper');
 
 #import('coreimpl.dart');
 
 #source('constant_map.dart');
 #source('date_helper.dart');
@@ skipping 1367 matching lines @@
   String toString() => "Closure";
 }
 
 bool jsHasOwnProperty(var jsObject, String property) {
   return JS('bool', @'$0.hasOwnProperty($1)', jsObject, property);
 }
 
 jsPropertyAccess(var jsObject, String property) {
   return JS('var', @'$0[$1]', jsObject, property);
 }
+
+
+// Called at the end of unaborted switch cases to get the (unique)
+// FallThroughError exception that will be thrown.
+FallThroughError fallThroughErrorInstance = null;
+getFallThroughError() {
+  // TODO(lrn): Redo when we support "const FallThroughError()".
+  if (fallThroughErrorInstance === null) {
+    fallThroughErrorInstance = new FallThroughError();
+  }
+  return fallThroughErrorInstance;
+}