Remove legacy restart code

runtime/vm/object_service.cc

 // Copyright (c) 2016, 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 "vm/debugger.h"
 #include "vm/disassembler.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ skipping 979 matching lines @@
 }
 
 
 void UnwindError::PrintJSONImpl(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Error", ref);
   jsobj.AddProperty("kind", "TerminationError");
   jsobj.AddServiceId(*this);
   jsobj.AddProperty("message", ToErrorCString());
   jsobj.AddProperty("_is_user_initiated", is_user_initiated());
-  jsobj.AddProperty("_is_vm_restart", is_vm_restart());
 }
 
 
 void Instance::PrintSharedInstanceJSON(JSONObject* jsobj, bool ref) const {
   AddCommonObjectProperties(jsobj, "Instance", ref);
   if (ref) {
     return;
   }
 
   // Add all fields in layout order, from superclass to subclass.
@@ skipping 572 matching lines @@
   jsobj.AddProperty("mirrorReferent", referent_handle);
 }
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 #endif
 
 }  // namespace dart