Added ES5 15.2.3.2 Object.getPrototypeOf.

src/v8natives.js

Index: src/v8natives.js
===================================================================
--- src/v8natives.js	(revision 3543)
+++ src/v8natives.js	(working copy)
@@ -449,6 +449,15 @@
 
 
 // ES5 section 15.2.3.5.
+function ObjectGetPrototypeOf(obj) {
+  if (!(IS_OBJECT(obj) || IS_FUNCTION(obj))) {
+    throw MakeTypeError("object_get_prototype_non_object", [obj]);
+  }
+  return obj.__proto__;
+}
+
+
+// ES5 section 15.2.3.5.
 function ObjectCreate(proto, properties) {
   if (!IS_OBJECT(proto) && !IS_NULL(proto)) {
     throw MakeTypeError("proto_object_or_null", [proto]);
@@ -512,7 +521,8 @@
   ));
   InstallFunctions($Object, DONT_ENUM, $Array(
     "keys", ObjectKeys,
-    "create", ObjectCreate
+    "create", ObjectCreate,
+    "getPrototypeOf", ObjectGetPrototypeOf
   ));
 }