Added Dartium changes onto 45.0.2454.104

LayoutTests/dart/Multiscript.dart

+// Copyright (c) 2011, 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.
+
+// Dart test for testing isolation across multiple script tags.
+library multiscript;
+import 'dart:js' as js;
+
+class State {
+  // Static stored in Dart so there is a unique value in each Dart DOM isolate.
+  static int sDart = 0;
+  static update() {
+    sDart++;
+    js.context['sJs']++;
+  }
+
+  // Static stored on the JS side of the world so there is one value for it
+  // across all Dart DOM isolates.
+  static int get sJs => js.context['sJs'];
+
+  static registerCallback(int index, Function callback) {
+    js.context.callMethod('registerCallback', [index, callback]);
+  }
+}