Introduce a PrototypeIterator template and use it all over the place

src/heap-snapshot-generator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/heap-snapshot-generator-inl.h"
 
 #include "src/allocation-tracker.h"
 #include "src/code-stubs.h"
 #include "src/conversions.h"
 #include "src/debug.h"
 #include "src/heap-profiler.h"
+#include "src/prototype-iterator.h"
 #include "src/types.h"
 
 namespace v8 {
 namespace internal {
 
 
 HeapGraphEdge::HeapGraphEdge(Type type, const char* name, int from, int to)
     : type_(type),
       from_index_(from),
       to_index_(to),
@@ skipping 1129 matching lines @@
 
 
 void V8HeapExplorer::ExtractJSObjectReferences(
     int entry, JSObject* js_obj) {
   HeapObject* obj = js_obj;
   ExtractClosureReferences(js_obj, entry);
   ExtractPropertyReferences(js_obj, entry);
   ExtractElementReferences(js_obj, entry);
   ExtractInternalReferences(js_obj, entry);
   SetPropertyReference(
-      obj, entry, heap_->proto_string(), js_obj->GetPrototype());
+      obj, entry, heap_->proto_string(), SAFE_GET_PROTOTYPE_FAST(js_obj));
   if (obj->IsJSFunction()) {
     JSFunction* js_fun = JSFunction::cast(js_obj);
     Object* proto_or_map = js_fun->prototype_or_initial_map();
     if (!proto_or_map->IsTheHole()) {
       if (!proto_or_map->IsMap()) {
         SetPropertyReference(
             obj, entry,
             heap_->prototype_string(), proto_or_map,
             NULL,
             JSFunction::kPrototypeOrInitialMapOffset);
@@ skipping 1997 matching lines @@
   writer_->AddString("\"<dummy>\"");
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 } }  // namespace v8::internal