ObjectGraph: Establish a HeapIterationScope *before* making the heap writable, least the sweeper in…

runtime/vm/service.cc

 // 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.
 
 #include "vm/service.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/globals.h"
 
@@ skipping 2321 matching lines @@
   }
   const Object& obj = Object::Handle(LookupHeapObject(thread, target_id, NULL));
   if (obj.raw() == Object::sentinel().raw() || !obj.IsClass()) {
     PrintInvalidParamError(js, "classId");
     return true;
   }
   const Class& cls = Class::Cast(obj);
   Array& storage = Array::Handle(Array::New(limit));
   GetInstancesVisitor visitor(cls, storage);
   ObjectGraph graph(thread);
+  HeapIterationScope iteration_scope(true);
   graph.IterateObjects(&visitor);
   intptr_t count = visitor.count();
   JSONObject jsobj(js);
   jsobj.AddProperty("type", "InstanceSet");
   jsobj.AddProperty("totalCount", count);
   {
     JSONArray samples(&jsobj, "samples");
     for (int i = 0; (i < storage.Length()) && (i < count); i++) {
       const Object& sample = Object::Handle(storage.At(i));
       samples.AddValue(sample);
@@ skipping 1771 matching lines @@
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart