Add support for capturing and changing the current isolate in the closure wrapper.

frog/leg/lib/js_helper.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.
 
 #library('js_helper');
 
 #import('coreimpl.dart');
 
 #source('constant_map.dart');
 #source('date_helper.dart');
@@ skipping 1328 matching lines @@
   Iterator iterator = keyValuePairs.iterator();
   Map result = new LinkedHashMap();
   while (iterator.hasNext()) {
     String key = iterator.next();
     var value = iterator.next();
     result[key] = value;
   }
   return result;
 }
 
+invokeClosure(Function closure,
+              var isolate,
+              int numberOfArguments,
+              var arg1,
+              var arg2) {
+  if (numberOfArguments == 0) {
+    return JS_CALL_IN_ISOLATE(isolate, () => closure());
+  } else if (numberOfArguments == 1) {
+    return JS_CALL_IN_ISOLATE(isolate, () => closure(arg1));
+  } else if (numberOfArguments == 2) {
+    return JS_CALL_IN_ISOLATE(isolate, () => closure(arg1, arg2));
+  } else {
+    throw new Exception(
+        'Unsupported number of arguments for wrapped closure');
+  }
+}
+
 /**
  * Called by generated code to convert a Dart closure to a JS
  * closure when the Dart closure is passed to the DOM.
  */
 convertDartClosureToJS(closure) {
   if (closure === null) return null;
   var function = JS('var', @'#.$identity', closure);
   if (JS('bool', @'!!#', function)) return function;
+
   function = JS("var", @"""function() {
-    var dartClosure = #;
-    switch (arguments.length) {
-      case 0: return #(dartClosure);
-      case 1: return #(dartClosure, arguments[0]);
-      case 2: return #(dartClosure, arguments[0], arguments[1]);
-      default:
-        throw new Error('Unsupported number of arguments for wrapped closure');
-    }
+    return #(#, #, arguments.length, arguments[0], arguments[1]);
   }""",
+  invokeClosure,
   closure,
-  callClosure0,
-  callClosure1,
-  callClosure2);
+  JS_CURRENT_ISOLATE());
+
   JS('void', @'#.$identity = #', closure, function);
   return function;
 }
 
 /**
- * Helper methods when converting a Dart closure to a JS closure.
- */
-callClosure0(closure) => closure();
-callClosure1(closure, arg1) => closure(arg1);
-callClosure2(closure, arg1, arg2) => closure(arg1, arg2);
-
-/**
  * Super class for Dart closures.
  */
 class Closure implements Function {
   String toString() => "Closure";
 }
 
 bool jsHasOwnProperty(var jsObject, String property) {
   return JS('bool', @'#.hasOwnProperty(#)', jsObject, property);
 }
 
 jsPropertyAccess(var jsObject, String property) {
   return JS('var', @'#[#]', jsObject, property);
 }
 
 /**
  * Called at the end of unaborted switch cases to get the singleton
  * FallThroughError exception that will be thrown.
  */
 getFallThroughError() => const FallThroughError();