Implemented Object.keys.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 052e875169dca83423298c5e63d84c2e747ea92d..d39eb71ac42405fdcef6fe44ccfe561141b4cff7 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -1988,7 +1988,9 @@ Local<Array> v8::Object::GetPropertyNames() {
   ENTER_V8;
   v8::HandleScope scope;
   i::Handle<i::JSObject> self = Utils::OpenHandle(this);
-  i::Handle<i::FixedArray> value = i::GetKeysInFixedArrayFor(self);
+  i::Handle<i::FixedArray> value = i::GetKeysInFixedArrayFor(
+      self,
+      i::INCLUDE_PROTOS);
   // Because we use caching to speed up enumeration it is important
   // to never change the result of the basic enumeration function so
   // we clone the result.