Added js and js_util to observatory deps

packages/js/js.dart

Index: packages/js/js.dart
diff --git a/packages/js/js.dart b/packages/js/js.dart
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+++ b/packages/js/js.dart
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+// Copyright (c) 2015, 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.
+
+/// Allows interoperability with Javascript APIs.
+library js;
+
+export 'dart:js' show allowInterop, allowInteropCaptureThis;
+
+/// A metadata annotation that indicates that a Library, Class, or member is
+/// implemented directly in JavaScript. All external members of a class or
+/// library with this annotation implicitly have it as well.
+///
+/// Specifying [name] customizes the JavaScript name to use. By default the
+/// dart name is used. It is not valid to specify a custom [name] for class
+/// instance members.
+class JS {
+  final String name;
+  const JS([this.name]);
+}
+
+class _Anonymous {
+  const _Anonymous();
+}
+
+/// A metadata annotation that indicates that a @JS annotated class is
+/// structural and does not have a known JavaScript prototype.
+///
+/// Factory constructors for anonymous JavaScript classes desugar to creating
+/// JavaScript object literals with name-value pairs corresponding to the
+/// parameter names and values.
+const _Anonymous anonymous = const _Anonymous();