Address a number of issues related to computation of currentScript and deferred loading.

dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.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.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 839 matching lines @@
     if (needsDefineClass) {
       copyFinishClasses.add(
           js('newIsolate.$finishClassesProperty = '
              '    oldIsolate.$finishClassesProperty'));
     }
 
     // function(oldIsolate) {
     return js.fun('oldIsolate', [
       js('var isolateProperties = oldIsolate.${namer.isolatePropertiesName}'),
 
-      js(r'isolateProperties.$currentScript = null'),
-
       js('var isolatePrototype = oldIsolate.prototype'),
       js('var str = "{\\n"'),
       js('str += "var properties = '
                      'arguments.callee.${namer.isolatePropertiesName};\\n"'),
       js('var hasOwnProperty = Object.prototype.hasOwnProperty'),
 
       // for (var staticName in isolateProperties) {
       js.forIn('staticName', 'isolateProperties', [
         js.if_('hasOwnProperty.call(isolateProperties, staticName)', [
           js('str += ("this." + staticName + "= properties." + staticName + '
@@ skipping 2083 matching lines @@
   function onLoad(event) {
     for (var i = 0; i < scripts.length; ++i) {
       scripts[i].removeEventListener('load', onLoad, false);
     }
     callback(event.target);
   }
   for (var i = 0; i < scripts.length; ++i) {
     scripts[i].addEventListener('load', onLoad, false);
   }
 })(function(currentScript) {
-  ${namer.isolateName}.${namer.isolatePropertiesName}.\$currentScript =
-      currentScript;
+  init.currentScript = currentScript;
 
   if (typeof console !== 'undefined' && typeof document !== 'undefined' &&
       document.readyState == "loading") {
     console.warn("Dart script executed synchronously, use <script src='" +
         currentScript.src + "' defer></scr" + "ipt> to execute after parsing " +
         "has completed. See also http://dartbug.com/12281.");
   }
   if (typeof dartMainRunner === "function") {
     dartMainRunner(function() { ${mainCall}; });
   } else {
@@ skipping 1136 matching lines @@
 
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;