Introduce a PrototypeIterator class and use it for prototype access

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index 94ff13e072036dc164141e3f75a91710bce84c3d..1e532912841005cd3e50f986ec9be8e3e3f472ed 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -14,6 +14,7 @@
 #include "src/heap-profiler.h"
 #include "src/ic-inl.h"
 #include "src/mark-compact.h"
+#include "src/prototype.h"
 #include "src/stub-cache.h"
 #include "src/vm-state-inl.h"
 
@@ -1091,11 +1092,13 @@ BUILTIN(GeneratorPoisonPill) {
 static inline Object* FindHidden(Heap* heap,
                                  Object* object,
                                  FunctionTemplateInfo* type) {
-  if (type->IsTemplateFor(object)) return object;
-  Object* proto = object->GetPrototype(heap->isolate());
-  if (proto->IsJSObject() &&
-      JSObject::cast(proto)->map()->is_hidden_prototype()) {
-    return FindHidden(heap, proto, type);
+  for (PrototypeIterator iter(heap->isolate(), object,
+                              PrototypeIterator::START_AT_RECEIVER);
+       !iter.IsAtEnd(PrototypeIterator::END_AT_NON_HIDDEN); iter.Advance()) {
+    ASSERT(!iter.GetCurrent()->IsJSProxy());

[Toon Verwaest, 2014/07/11 09:41:28]

What about returning heap->null_value() if iter.GetCurrent()->IsJSProxy()?

+    if (type->IsTemplateFor(iter.GetCurrent())) {
+      return iter.GetCurrent();
+    }
   }
   return heap->null_value();
 }