A few API changes:

sdk/lib/js/dartium/js_dartium.dart

 // Copyright (c) 2013, 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.
 
-/**
- * The js.dart library provides simple JavaScript invocation from Dart that
- * works on both Dartium and on other modern browsers via Dart2JS.
- *
- * It provides a model based on scoped [JsObject] objects.  Proxies give Dart
- * code access to JavaScript objects, fields, and functions as well as the
- * ability to pass Dart objects and functions to JavaScript functions.  Scopes
- * enable developers to use proxies without memory leaks - a common challenge
- * with cross-runtime interoperation.
- *
- * The top-level [context] getter provides a [JsObject] to the global JavaScript
- * context for the page your Dart code is running on.  In the following example:
- *
- *     import 'dart:js';
- *
- *     void main() {
- *       context.callMethod('alert', ['Hello from Dart via JavaScript']);
- *     }
- *
- * context['alert'] creates a proxy to the top-level alert function in
- * JavaScript.  It is invoked from Dart as a regular function that forwards to
- * the underlying JavaScript one.  By default, proxies are released when
- * the currently executing event completes, e.g., when main is completes
- * in this example.
- *
- * The library also enables JavaScript proxies to Dart objects and functions.
- * For example, the following Dart code:
- *
- *     context['dartCallback'] = new Callback.once((x) => print(x*2));
- *
- * defines a top-level JavaScript function 'dartCallback' that is a proxy to
- * the corresponding Dart function.  The [Callback.once] constructor allows the
- * proxy to the Dart function to be retained across multiple events;
- * instead it is released after the first invocation.  (This is a common
- * pattern for asychronous callbacks.)
- *
- * Note, parameters and return values are intuitively passed by value for
- * primitives and by reference for non-primitives.  In the latter case, the
- * references are automatically wrapped and unwrapped as proxies by the library.
- *
- * This library also allows construction of JavaScripts objects given a
- * [JsObject] to a corresponding JavaScript constructor.  For example, if the
- * following JavaScript is loaded on the page:
- *
- *     function Foo(x) {
- *       this.x = x;
- *     }
- *
- *     Foo.prototype.add = function(other) {
- *       return new Foo(this.x + other.x);
- *     }
- *
- * then, the following Dart:
- *
- *     var foo = new JsObject(context['Foo'], [42]);
- *     var foo2 = foo.callMethod('add', [foo]);
- *     print(foo2['x']);
- *
- * will construct a JavaScript Foo object with the parameter 42, invoke its
- * add method, and return a [JsObject] to a new Foo object whose x field is 84.
- */
-
 library dart.js;
 
-import 'dart:collection' show HashMap;
-import 'dart:html';
-import 'dart:isolate';
+import 'dart:nativewrappers';
 
-// Global ports to manage communication from Dart to JS.
+JsObject _cachedContext;
 
-SendPortSync _jsPortSync = window.lookupPort('dart-js-context');
-SendPortSync _jsPortCreate = window.lookupPort('dart-js-create');
-SendPortSync _jsPortInstanceof = window.lookupPort('dart-js-instanceof');
-SendPortSync _jsPortDeleteProperty = window.lookupPort('dart-js-delete-property');
-SendPortSync _jsPortConvert = window.lookupPort('dart-js-convert');
+JsObject get _context native "Js_context_Callback";
 
-final String _objectIdPrefix = 'dart-obj-ref';
-final String _functionIdPrefix = 'dart-fun-ref';
-final _objectTable = new _ObjectTable();
-final _functionTable = new _ObjectTable.forFunctions();
-
-// Port to handle and forward requests to the underlying Dart objects.
-// A remote proxy is uniquely identified by an ID and SendPortSync.
-ReceivePortSync _port = new ReceivePortSync()
-    ..receive((msg) {
-      try {
-        var id = msg[0];
-        var method = msg[1];
-        if (method == '#call') {
-          var receiver = _getObjectTable(id).get(id);
-          var result;
-          if (receiver is Function) {
-            // remove the first argument, which is 'this', but never
-            // used for a raw function
-            var args = msg[2].sublist(1).map(_deserialize).toList();
-            result = Function.apply(receiver, args);
-          } else if (receiver is Callback) {
-            var args = msg[2].map(_deserialize).toList();
-            result = receiver._call(args);
-          } else {
-            throw new StateError('bad function type: $receiver');
-          }
-          return ['return', _serialize(result)];
-        } else {
-          // TODO(vsm): Support a mechanism to register a handler here.
-          throw 'Invocation unsupported on non-function Dart proxies';
-        }
-      } catch (e) {
-        // TODO(vsm): callSync should just handle exceptions itself.
-        return ['throws', '$e'];
-      }
-    });
-
-_ObjectTable _getObjectTable(String id) {
-  if (id.startsWith(_functionIdPrefix)) return _functionTable;
-  if (id.startsWith(_objectIdPrefix)) return _objectTable;
-  throw new ArgumentError('internal error: invalid object id: $id');
+JsObject get context {
+  if (_cachedContext == null) {
+    _cachedContext = _context;
+  }
+  return _cachedContext;
 }
 
-JsObject _context;
+class JsObject extends NativeFieldWrapperClass2 {
+  JsObject.internal();
 
-/**
- * Returns a proxy to the global JavaScript context for this page.
- */
-JsObject get context {
-  if (_context == null) {
-    var port = _jsPortSync;
-    if (port == null) {
-      return null;
+  factory JsObject(JsFunction constructor, [List arguments]) => _create(constructor, arguments);
+
+  static JsObject _create(JsFunction constructor, arguments) native "JsObject_constructorCallback";
+
+   /**
+    * Expert users only:
+    * Use this constructor only if you want to gain access to JS expandos
+    * attached to a browser native object such as a Node.
+    * Not all native browser objects can be converted using fromBrowserObject.
+    * Currently the following types are supported:
+    * * Node
+    * * ArrayBuffer
+    * * Blob
+    * * ImageData
+    * * IDBKeyRange
+    * TODO(jacobr): support Event, Window and NodeList as well.
+    */
+  factory JsObject.fromBrowserObject(var object) {
+    if (object is num || object is String || object is bool || object == null) {
+      throw new ArgumentError(
+        "object cannot be a num, string, bool, or null");
     }
-    _context = _deserialize(_jsPortSync.callSync([]));
-  }
-  return _context;
-}
-
-/**
- * Converts a json-like [data] to a JavaScript map or array and return a
- * [JsObject] to it.
- */
-JsObject jsify(dynamic data) => data == null ? null : new JsObject._json(data);
-
-/**
- * Converts a local Dart function to a callback that can be passed to
- * JavaScript.
- */
-class Callback implements Serializable<JsFunction> {
-  final bool _withThis;
-  final Function _function;
-  JsFunction _jsFunction;
-
-  Callback._(this._function, this._withThis) {
-    var id = _functionTable.add(this);
-    _jsFunction = new JsFunction._internal(_port.toSendPort(), id);
-  }
-
-  factory Callback(Function f) => new Callback._(f, false);
-  factory Callback.withThis(Function f) => new Callback._(f, true);
-
-  dynamic _call(List args) {
-    var arguments = (_withThis) ? args : args.sublist(1);
-    return Function.apply(_function, arguments);
-  }
-
-  JsFunction toJs() => _jsFunction;
-}
-
-/**
- * Proxies to JavaScript objects.
- */
-class JsObject implements Serializable<JsObject> {
-  final SendPortSync _port;
-  final String _id;
-
-  /**
-   * Constructs a [JsObject] to a new JavaScript object by invoking a (proxy to
-   * a) JavaScript [constructor].  The [arguments] list should contain either
-   * primitive values, DOM elements, or Proxies.
-   */
-  factory JsObject(Serializable<JsFunction> constructor, [List arguments]) {
-    final params = [constructor];
-    if (arguments != null) params.addAll(arguments);
-    final serialized = params.map(_serialize).toList();
-    final result = _jsPortCreate.callSync(serialized);
-    return _deserialize(result);
+    return _fromBrowserObject(object);
   }
 
   /**
-   * Constructs a [JsObject] to a new JavaScript map or list created defined via
-   * Dart map or list.
+   * Converts a json-like [object] to a JavaScript map or array and return a
+   * [JsObject] to it.
    */
-  factory JsObject._json(data) => _convert(data);
-
-  static _convert(data) =>
-      _deserialize(_jsPortConvert.callSync(_serializeDataTree(data)));
-
-  static _serializeDataTree(data) {
-    if (data is Map) {
-      final entries = new List();
-      for (var key in data.keys) {
-        entries.add([key, _serializeDataTree(data[key])]);
-      }
-      return ['map', entries];
-    } else if (data is Iterable) {
-      return ['list', data.map(_serializeDataTree).toList()];
-    } else {
-      return ['simple', _serialize(data)];
+  factory JsObject.jsify(object) {
+    if ((object is! Map) && (object is! Iterable)) {
+      throw new ArgumentError("object must be a Map or Iterable");
     }
+    return _jsify(object);
   }
 
-  JsObject._internal(this._port, this._id);
+  static JSObject _jsify(object) native "JsObject_jsify";
 
-  JsObject toJs() => this;
+  static JsObject _fromBrowserObject(object) native "JsObject_fromBrowserObject";
 
-  // Resolve whether this is needed.
-  operator[](arg) => _forward(this, '[]', 'method', [ arg ]);
+  operator[](key) native "JsObject_[]";
+  operator[]=(key, value) native "JsObject_[]=";
 
-  // Resolve whether this is needed.
-  operator[]=(key, value) => _forward(this, '[]=', 'method', [ key, value ]);
+  int get hashCode native "JsObject_hashCode";
 
-  int get hashCode => _id.hashCode;
+  operator==(other) => other is JsObject && _identityEquality(this, other);
 
-  // Test if this is equivalent to another Proxy.  This essentially
-  // maps to JavaScript's === operator.
-  operator==(other) => other is JsObject && this._id == other._id;
+  static bool _identityEquality(JsObject a, JsObject b) native "JsObject_identityEquality";
 
-  /**
-   * Check if this [JsObject] has a [name] property.
-   */
-  bool hasProperty(String name) => _forward(this, name, 'hasProperty', []);
+  bool hasProperty(String property) native "JsObject_hasProperty";
 
-  /**
-   * Delete the [name] property.
-   */
-  void deleteProperty(String name) {
-    _jsPortDeleteProperty.callSync([this, name].map(_serialize).toList());
-  }
+  void deleteProperty(JsFunction name) native "JsObject_deleteProperty";
 
-  /**
-   * Check if this [JsObject] is instance of [type].
-   */
-  bool instanceof(Serializable<JsFunction> type) =>
-      _jsPortInstanceof.callSync([this, type].map(_serialize).toList());
+  bool instanceof(JsFunction type) native "JsObject_instanceof";
 
   String toString() {
     try {
-      return _forward(this, 'toString', 'method', []);
+      return _toString();
     } catch(e) {
       return super.toString();
     }
   }
 
+  String _toString() native "JsObject_toString";
+
   callMethod(String name, [List args]) {
-    return _forward(this, name, 'method', args != null ? args : []);
-  }
-
-  // Forward member accesses to the backing JavaScript object.
-  static _forward(JsObject receiver, String member, String kind, List args) {
-    var result = receiver._port.callSync([receiver._id, member, kind,
-                                          args.map(_serialize).toList()]);
-    switch (result[0]) {
-      case 'return': return _deserialize(result[1]);
-      case 'throws': throw _deserialize(result[1]);
-      case 'none':
-          throw new NoSuchMethodError(receiver, new Symbol(member), args, {});
-      default: throw 'Invalid return value';
-    }
-  }
-}
-
-/// A [JsObject] subtype to JavaScript functions.
-class JsFunction extends JsObject implements Serializable<JsFunction> {
-  JsFunction._internal(SendPortSync port, String id)
-      : super._internal(port, id);
-
-  apply(thisArg, [List args]) {
-    return JsObject._forward(this, '', 'apply',
-        [thisArg]..addAll(args == null ? [] : args));
-  }
-}
-
-/// Marker class used to indicate it is serializable to js. If a class is a
-/// [Serializable] the "toJs" method will be called and the result will be used
-/// as value.
-abstract class Serializable<T> {
-  T toJs();
-}
-
-class _ObjectTable {
-  final String name;
-  final Map<String, Object> objects;
-  final Map<Object, String> ids;
-  int nextId = 0;
-
-  // Creates a table that uses an identity Map to store IDs
-  _ObjectTable()
-    : name = _objectIdPrefix,
-      objects = new HashMap<String, Object>(),
-      ids = new HashMap<Object, String>.identity();
-
-  // Creates a table that uses an equality-based Map to store IDs, since
-  // closurized methods may be equal, but not identical
-  _ObjectTable.forFunctions()
-    : name = _functionIdPrefix,
-      objects = new HashMap<String, Object>(),
-      ids = new HashMap<Object, String>();
-
-  // Adds a new object to the table. If [id] is not given, a new unique ID is
-  // generated. Returns the ID.
-  String add(Object o, {String id}) {
-    // TODO(vsm): Cache x and reuse id.
-    if (id == null) id = ids[o];
-    if (id == null) id = '$name-${nextId++}';
-    ids[o] = id;
-    objects[id] = o;
-    return id;
-  }
-
-  // Gets an object by ID.
-  Object get(String id) => objects[id];
-
-  bool contains(String id) => objects.containsKey(id);
-
-  String getId(Object o) => ids[o];
-
-  // Gets the current number of objects kept alive by this table.
-  get count => objects.length;
-}
-
-// Dart serialization support.
-
-_serialize(var message) {
-  if (message == null) {
-    return null;  // Convert undefined to null.
-  } else if (message is String ||
-             message is num ||
-             message is bool) {
-    // Primitives are passed directly through.
-    return message;
-  } else if (message is SendPortSync) {
-    // Non-proxied objects are serialized.
-    return message;
-  } else if (message is JsFunction) {
-    // Remote function proxy.
-    return ['funcref', message._id, message._port];
-  } else if (message is JsObject) {
-    // Remote object proxy.
-    return ['objref', message._id, message._port];
-  } else if (message is Serializable) {
-    // use of result of toJs()
-    return _serialize(message.toJs());
-  } else if (message is Function) {
-    var id = _functionTable.getId(message);
-    if (id != null) {
-      return ['funcref', id, _port.toSendPort()];
-    }
-    id = _functionTable.add(message);
-    return ['funcref', id, _port.toSendPort()];
-  } else {
-    // Local object proxy.
-    return ['objref', _objectTable.add(message), _port.toSendPort()];
-  }
-}
-
-_deserialize(var message) {
-  deserializeFunction(message) {
-    var id = message[1];
-    var port = message[2];
-    if (port == _port.toSendPort()) {
-      // Local function.
-      return _functionTable.get(id);
-    } else {
-      // Remote function.
-      var jsFunction = _functionTable.get(id);
-      if (jsFunction == null) {
-        jsFunction = new JsFunction._internal(port, id);
-        _functionTable.add(jsFunction, id: id);
+    try {
+      return _callMethod(name, args);
+    } catch(e) {
+      if (hasProperty(name)) {
+        rethrow;
+      } else {
+        throw new NoSuchMethodError(this, new Symbol(name), args, null);
       }
-      return jsFunction;
     }
   }
 
-  deserializeObject(message) {
-    var id = message[1];
-    var port = message[2];
-    if (port == _port.toSendPort()) {
-      // Local object.
-      return _objectTable.get(id);
-    } else {
-      // Remote object.
-      var jsObject = _objectTable.get(id);
-      if (jsObject == null) {
-        jsObject = new JsObject._internal(port, id);
-        _objectTable.add(jsObject, id: id);
-      }
-      return jsObject;
-    }
-  }
+  _callMethod(String name, List args) native "JsObject_callMethod";
+}
 
-  if (message == null) {
-    return null;  // Convert undefined to null.
-  } else if (message is String ||
-             message is num ||
-             message is bool) {
-    // Primitives are passed directly through.
-    return message;
-  } else if (message is SendPortSync) {
-    // Serialized type.
-    return message;
-  }
-  var tag = message[0];
-  switch (tag) {
-    case 'funcref': return deserializeFunction(message);
-    case 'objref': return deserializeObject(message);
-  }
-  throw 'Unsupported serialized data: $message';
+class JsFunction extends JsObject {
+  JsFunction.internal();
+
+  /**
+   * Returns a [JsFunction] that captures its 'this' binding and calls [f]
+   * with the value of this passed as the first argument.
+   */
+  factory JsFunction.withThis(Function f) => _withThis(f);
+
+  apply(List args, {thisArg}) native "JsFunction_apply";
+
+  static JsFunction _withThis(Function f) native "JsFunction_withThis";
 }