Only add JS once, and not to very single patched library.

lib/compiler/implementation/native_handler.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('native');
 #import('dart:uri');
 #import('leg.dart');
 #import('elements/elements.dart');
 #import('js_backend/js_backend.dart');
 #import('scanner/scannerlib.dart');
@@ skipping 65 matching lines @@
 void maybeEnableNative(Compiler compiler,
                        LibraryElement library,
                        Uri uri) {
   String libraryName = uri.toString();
   if (library.entryCompilationUnit.script.name.contains(
           'dart/tests/compiler/dart2js_native')
       || libraryName == 'dart:dom_deprecated'
       || libraryName == 'dart:isolate'
       || libraryName == 'dart:html') {
     library.canUseNative = true;
-    library.addToScope(compiler.findHelper(const SourceString('JS')), compiler);
+    compiler.addForeignFunctions(library);

[ahe, 2012/08/21 11:28:31]

I'm not sure about this. What do you need?

[Anders Johnsen, 2012/08/21 11:40:23]

The problem is not here, but in the other file. We add JS scope to every library
that is being patches. This was okay before the latest changes, but the library
and the patch library is one and same library. This means that if we patch
isolate, we'll end up adding JS twice. My argument is that we should only add JS
(and the other helper methods in ForeignFunctions) here, and _only_ here.

[ahe, 2012/08/21 12:01:16]

I don't think the patch libraries need all the foreign functions. Some of them
are pretty powerful and should only be used in our interceptors.

If you're unifying dart:isolate, then I don't think you should need to enable
native at all for the isolate library.

[Anders Johnsen, 2012/08/21 14:31:11]

Thank you for explaining, I've reverted this particular change. I agree, don't
expose more then needed!

     if (compiler.jsIndexingBehaviorInterface !== null) {
       library.addToScope(compiler.jsIndexingBehaviorInterface, compiler);
     }
   }
 }
 
 void checkAllowedLibrary(ElementListener listener, Token token) {
   LibraryElement currentLibrary = listener.compilationUnitElement.getLibrary();
   if (!currentLibrary.canUseNative) {
     listener.recoverableError("Unexpected token", token: token);
@@ skipping 236 matching lines @@
                                       String parameters) {
   buffer.add("  if (Object.getPrototypeOf(this).hasOwnProperty");
   buffer.add("('$methodName')) {\n");
   buffer.add("  $code");
   buffer.add("  } else {\n");
   buffer.add("    return Object.prototype.$methodName.call(this");
   buffer.add(parameters == '' ? '' : ', $parameters');
   buffer.add(");\n");
   buffer.add("  }\n");
 }