Handle for-in loops

lib/runtime/dart/_isolate_helper.js

Index: lib/runtime/dart/_isolate_helper.js
diff --git a/lib/runtime/dart/_isolate_helper.js b/lib/runtime/dart/_isolate_helper.js
index 839a902908e3db5e27112875e609b18bd5218a76..ea15bb99d53620f46b8f878e646a7cdb95352df7 100644
--- a/lib/runtime/dart/_isolate_helper.js
+++ b/lib/runtime/dart/_isolate_helper.js
@@ -709,14 +709,14 @@ var _isolate_helper;
         dart.dinvoke(this[_scheduledControlEvents], 'clear');
       }
       for (let port of this.ports.values) {
-        dart.dinvoke(port, '_close');
+        port._close();
       }
       this.ports.clear();
       this.weakPorts.clear();
       exports._globalState.isolates.remove(this.id);
       this.errorPorts.clear();
       if (this.doneHandlers !== null) {
-        for (let port of this.doneHandlers) {
+        for (let port of dart.as(this.doneHandlers, core.Iterable$(isolate.SendPort))) {
           port.send(null);
         }
         this.doneHandlers = null;