Implement Object.keys for proxies.

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 831dd14ef84b233764946a02aef650ac86a8ea04..2759819a5fca408128e241975eb53b2b9f66adf1 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -308,6 +308,13 @@ function ObjectLookupSetter(name) {
 function ObjectKeys(obj) {
   if (!IS_SPEC_OBJECT(obj))
     throw MakeTypeError("obj_ctor_property_non_object", ["keys"]);
+  if (%IsJSProxy(obj)) {
+    var handler = %GetHandler(obj);
+    var keys = handler.keys;
+    if (IS_UNDEFINED(keys)) keys = DerivedKeysTrap;
+    var names = keys.call(handler);

[Mads Ager (chromium), 2011/07/12 13:28:19]

Do you want to rely on Function.prototype.call here or do you want to use
%_CallFunction(handler, keys)?

[rossberg, 2011/07/13 10:11:52]

Done, here and in a few other places. (Btw, who picked the argument order of
that built-in??)

[Mads Ager (chromium), 2011/07/13 10:17:25]

I don't remember. I would have preferred having the function first... :-)

+    return ToStringArray(names);
+  }
   return %LocalKeys(obj);
 }