Add a new magic element type for annotating types that have Javascript array behavior.

lib/compiler/implementation/native_handler.dart

Index: lib/compiler/implementation/native_handler.dart
===================================================================
--- lib/compiler/implementation/native_handler.dart	(revision 8103)
+++ lib/compiler/implementation/native_handler.dart	(working copy)
@@ -83,6 +83,7 @@
     library.define(new ForeignElement(
         const SourceString('native'), library), compiler);
     library.canUseNative = true;
+    library.define(compiler.javaScriptIndexingBehaviorInterface, compiler);

[ahe, 2012/06/12 18:30:04]

For the unit tests, it may make sense to test for null here.

[ngeoffray, 2012/06/13 13:02:42]

Done.

   }
 
   // Additionaly, if this is a test, we allow access to foreign functions.