Use "self" instead of globalThis.

dart/sdk/lib/js/dart2js/js_dart2js.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.
 
 /**
  * Support for interoperating with JavaScript.
  *
  * This library provides access to JavaScript objects from Dart, allowing
  * Dart code to get and set properties, and call methods of JavaScript objects
  * and invoke JavaScript functions. The library takes care of converting
@@ skipping 79 matching lines @@
 import 'dart:html' show Blob, Event, ImageData, Node, Window;
 import 'dart:collection' show HashMap, ListMixin;
 import 'dart:indexed_db' show KeyRange;
 import 'dart:typed_data' show TypedData;
 
 import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
 import 'dart:_interceptors' show JavaScriptObject, UnknownJavaScriptObject;
 import 'dart:_js_helper' show Primitives, convertDartClosureToJS,
     getIsolateAffinityTag;
 
-final JsObject context = _wrapToDart(Primitives.computeGlobalThis());
+final JsObject context = _wrapToDart(JS('', 'self'));
 
 _convertDartFunction(Function f, {bool captureThis: false}) {
   return JS('',
     'function(_call, f, captureThis) {'
       'return function() {'
         'return _call(f, captureThis, this, '
             'Array.prototype.slice.apply(arguments));'
       '}'
     '}(#, #, #)', DART_CLOSURE_TO_JS(_callDartFunction), f, captureThis);
 }
@@ skipping 462 matching lines @@
   // Dart in that context. The JS object will have a cached proxy
   // but it won't be a valid Dart object in this context.
   // For now we throw away the cached proxy, but we should be able
   // to cache proxies from multiple JS contexts and Dart isolates.
   if (dartProxy == null || !_isLocalObject(o)) {
     dartProxy = createProxy(o);
     _defineProperty(o, propertyName, dartProxy);
   }
   return dartProxy;
 }