Fix double-closing of handles in Windows EventHandler.

runtime/bin/eventhandler_win.h

Index: runtime/bin/eventhandler_win.h
diff --git a/runtime/bin/eventhandler_win.h b/runtime/bin/eventhandler_win.h
index 92741a537e38af2b672452c1871709361c367e5c..ac7c27dfdd045e7de3f75d88cf009fd4b0eaaf21 100644
--- a/runtime/bin/eventhandler_win.h
+++ b/runtime/bin/eventhandler_win.h
@@ -340,12 +340,14 @@ class DirectoryWatchHandle : public Handle {
   DirectoryWatchHandle(HANDLE handle, int events, bool recursive)
       : Handle(handle),
         events_(events),
-        recursive_(recursive) {
+        recursive_(recursive),
+        closed_(false) {
     type_ = kDirectoryWatch;
   }
 
   virtual void EnsureInitialized(EventHandlerImplementation* event_handler);
   virtual bool IsClosed();
+  virtual void DoClose();
 
   virtual bool IssueRead();
 
@@ -354,6 +356,7 @@ class DirectoryWatchHandle : public Handle {
  private:
   int events_;
   bool recursive_;
+  bool closed_;
 };