Remove proxying support from dart:html

tests/html/js_interop_obj_invoke_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
-
-#library('JsInteropObjInvokeTest');
-#import('../../pkg/unittest/unittest.dart');
-#import('../../pkg/unittest/html_config.dart');
-#import('dart:html');
-#import('dart:isolate');
-
-injectSource(code) {
-  final script = new ScriptElement();
-  script.type = 'text/javascript';
-  script.innerHTML = code;
-  document.body.nodes.add(script);
-}
-
-var jsProxyTest = """
-  function TestType(x) {
-    this.x = x;
-  }
-  TestType.prototype.razzle = function () {
-    return this.x * 2;
-  }
-  var data = new TestType(21);
-
-  var port = window.lookupPort('test1');
-  port.callSync(data);
-""";
-
-main() {
-  useHtmlConfiguration();
-
-  test('js-proxy', () {
-    int invoked = 0;
-
-    var port = new ReceivePortSync();
-    port.receive((data) {
-      expect(data.x, equals(21));
-      expect(data.razzle(), equals(42));
-      data.x = 100;
-      expect(data.razzle(), equals(200));
-
-      ++invoked;
-    });
-    window.registerPort('test1', port.toSendPort());
-
-    injectSource(jsProxyTest);
-    expect(invoked, equals(1));
-  });
-}