Do not allow a hot reload if the isolate has a sticky error

runtime/vm/json_stream.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_JSON_STREAM_H_
 #define VM_JSON_STREAM_H_
 
 #include "include/dart_api.h"  // for Dart_Port
 #include "platform/text_buffer.h"
 #include "vm/allocation.h"
@@ skipping 42 matching lines @@
   kStreamNotSubscribed       = 104,
   kIsolateMustBeRunnable     = 105,
   kIsolateMustBePaused       = 106,
 
   // Experimental (used in private rpcs).
   kIsolateIsReloading        = 1000,
   kFileSystemAlreadyExists   = 1001,
   kFileSystemDoesNotExist    = 1002,
   kFileDoesNotExist          = 1003,
   kIsolateReloadFailed       = 1004,
+  kIsolateReloadBarred       = 1005,
 };
 
 // Expected that user_data is a JSONStream*.
 void AppendJSONStreamConsumer(Dart_StreamConsumer_State state,
                               const char* stream_name,
                               const uint8_t* buffer,
                               intptr_t buffer_length,
                               void* user_data);
 
 class JSONStream : ValueObject {
@@ skipping 354 matching lines @@
 
   friend class JSONObject;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(JSONArray);
 };
 
 }  // namespace dart
 
 #endif  // VM_JSON_STREAM_H_