Always store stubs on the JSObject receiver, even when in slow mode.

src/ic-inl.h

Index: src/ic-inl.h
diff --git a/src/ic-inl.h b/src/ic-inl.h
index e6ff2daa62b5feb8b67b2cc4fb64a21f310cedef..06cbf2e1128ff111b8affb358195568cb665425c 100644
--- a/src/ic-inl.h
+++ b/src/ic-inl.h
@@ -102,9 +102,8 @@ void IC::SetTargetAtAddress(Address address, Code* target) {
 
 InlineCacheHolderFlag IC::GetCodeCacheForObject(Object* object,
                                                 JSObject* holder) {
-  if (object->IsJSObject()) {
-    return GetCodeCacheForObject(JSObject::cast(object), holder);
-  }
+  if (object->IsJSObject()) return OWN_MAP;
+
   // If the object is a value, we use the prototype map for the cache.
   ASSERT(object->IsString() || object->IsSymbol() ||
          object->IsNumber() || object->IsBoolean());
@@ -112,23 +111,6 @@ InlineCacheHolderFlag IC::GetCodeCacheForObject(Object* object,
 }
 
 
-InlineCacheHolderFlag IC::GetCodeCacheForObject(JSObject* object,
-                                                JSObject* holder) {
-  // Fast-properties and global objects store stubs in their own maps.
-  // Slow properties objects use prototype's map (unless the property is its own
-  // when holder == object). It works because slow properties objects having
-  // the same prototype (or a prototype with the same map) and not having
-  // the property are interchangeable for such a stub.
-  if (holder != object &&
-      !object->HasFastProperties() &&
-      !object->IsJSGlobalProxy() &&
-      !object->IsJSGlobalObject()) {
-    return PROTOTYPE_MAP;
-  }
-  return OWN_MAP;
-}
-
-
 JSObject* IC::GetCodeCacheHolder(Isolate* isolate,
                                  Object* object,
                                  InlineCacheHolderFlag holder) {