isolate: fix how we get the current script now that frog automatically wraps the

lib/isolate/frog/natives.js

 // 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.
 
 // Top-level native code needed by the frog compiler
 
 var $globalThis = this;
 var $globals = null;
 var $globalState = null;
+var $thisScriptUrl = null;
+var $isWorker = typeof ($globalThis['importScripts']) != 'undefined';
+var $supportsWorkers =
+    $isWorker || ((typeof $globalThis['Worker']) != 'undefined');
 function $initGlobals(context) { context.isolateStatics = {}; }
 function $setGlobals(context) { $globals = context.isolateStatics; }
 
 // Wrap a 0-arg dom-callback to bind it with the current isolate:
 function $wrap_call$0(fn) { return fn && fn.wrap$call$0(); }
 
 Function.prototype.wrap$call$0 = function() {
   var isolateContext = $globalState.currentContext;
   var self = this;
   this.wrap$0 = function() {
@@ skipping 12 matching lines @@
   var isolateContext = $globalState.currentContext;
   var self = this;
   this.wrap$1 = function(arg) {
     var res = isolateContext.eval(function() { return self(arg); });
     $globalState.topEventLoop.run();
     return res;
   };
   this.wrap$call$1 = function() { return this.wrap$1; };
   return this.wrap$1;
 };
+
+$thisScriptUrl = (function () {
+  if (!$supportsWorkers || $isWorker) return (void 0);
+
+  // TODO(5334778): Find a cross-platform non-brittle way of getting the
+  // currently running script.
+  var scripts = document.getElementsByTagName('script');
+  // The scripts variable only contains the scripts that have already been
+  // executed. The last one is the currently running script.
+  var script = scripts[scripts.length - 1];
+  var src = script && script.src;
+  if (!src) {
+    // TODO()
+    src = "FIXME:5407062" + "_" + Math.random().toString();
+    if (script) script.src = src;
+  }
+  return src;
+})();