Avoid needless int64_t to intptr_t conversion in eventhandler.

runtime/bin/eventhandler.cc

 // 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.
 
 #include "bin/dartutils.h"
 #include "bin/eventhandler.h"
 #include "bin/socket.h"
 
 #include "include/dart_api.h"
 
@@ skipping 54 matching lines @@
   Dart_Handle sender = Dart_GetNativeArgument(args, 1);
   intptr_t id = kInvalidId;
   if (Dart_IsNull(sender)) {
     id = kTimerId;
   } else {
     Socket::GetSocketIdNativeField(sender, &id);
   }
   handle = Dart_GetNativeArgument(args, 2);
   Dart_Port dart_port =
       DartUtils::GetIntegerField(handle, DartUtils::kIdFieldName);
-  intptr_t data = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 3));
+  int64_t data = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 3));
   event_handler->SendData(id, dart_port, data);
   Dart_ExitScope();
 }