Changes to named property callbacks API

[Anton Muhin]

Dear v8 users,

[if you don't use named property query callbacks, you may stop right now]

We've started a process of migration to new named property query
callbacks which returns Handle<Integer> instead of Handle<Boolean>.
That would allow better control over attributes of intercepted
properties.

The recommended migration plan is:

1. As of v8 2.2.15 (r4809,
http://code.google.com/p/v8/source/detail?r=4809, r4797 of bleeding
edge, http://code.google.com/p/v8/source/detail?r=4797) to enable new
API one needs to define USE_NEW_QUERY_CALLBACKS before include of
v8.h. That would produce compilation errors in case you use named
query callbacks. The recommended migration is:
* if you return empty handle (v8::Handle<v8::Boolean>()) from the
callback, return empty handle but of Integer type
(v8::Handle<v8::Integer>())
* if you return v8::True(), then if intercepted property is
enumerated by your enumerate callback, then return
v8::Integer::New(v8::None), otherwise return
v8::Integer::New(v8::DontEnum)
* if you return v8::False, most probably you meant empty handle.
If there are cases when you think v8::False is mandatory, please, let
us know.

2. (approx. mid of next week), new API would be used by default. That
_would lead_ to compilation errors unless you already have migrated to
new API (see 1. above)

If you have any problems migrating to new API, please, let us know.

yours,
anton.