One event handler for all isolates

runtime/bin/isolate_data.h

Index: runtime/bin/isolate_data.h
diff --git a/runtime/bin/isolate_data.h b/runtime/bin/isolate_data.h
index 2992a08184e54c710efbbaac9b9de5b3bae25528..df76864f89ddac45d616664004a03844404fe792 100644
--- a/runtime/bin/isolate_data.h
+++ b/runtime/bin/isolate_data.h
@@ -21,11 +21,10 @@ class EventHandler;
 class IsolateData {
  public:
   IsolateData()
-      : event_handler(NULL), object_array_class(NULL),
+      : object_array_class(NULL),
         growable_object_array_class(NULL), immutable_array_class(NULL) {
   }
 
-  EventHandler* event_handler;
   Dart_PersistentHandle object_array_class;
   Dart_PersistentHandle growable_object_array_class;
   Dart_PersistentHandle immutable_array_class;