Proxies: Make 'with' work, plus minor other fixes

src/proxy.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 174 matching lines @@
   return enumerableNames
 }
 
 function DerivedEnumerateTrap() {
   var names = this.getPropertyNames()
   var enumerableNames = []
   for (var i = 0, count = 0; i < names.length; ++i) {
     var name = names[i]
     if (IS_SYMBOL(name)) continue
     var desc = this.getPropertyDescriptor(TO_STRING_INLINE(name))
-    if (!IS_UNDEFINED(desc) && desc.enumerable) {
-      enumerableNames[count++] = names[i]
+    if (!IS_UNDEFINED(desc)) {
+      if (!desc.configurable) {
+        throw MakeTypeError("proxy_prop_not_configurable",
+            [this, "getPropertyDescriptor", name])
+      }
+      if (desc.enumerable) enumerableNames[count++] = names[i]

[Yang, 2013/07/19 12:05:43]

We use semicolons pretty sparingly in this file. Is there any reason for this?

[rossberg, 2013/07/19 14:05:02]

Aesthetics? :)

     }
   }
   return enumerableNames
 }
 
 function ProxyEnumerate(proxy) {
   var handler = %GetHandler(proxy)
   if (IS_UNDEFINED(handler.enumerate)) {
     return %Apply(DerivedEnumerateTrap, handler, [], 0, 0)
   } else {
     return ToNameArray(handler.enumerate(), "enumerate", false)
   }
 }