Small API improvements:

Small API improvements:

 * Added Get and Set taking uint32_t for faster and more convenient
   access to elements.

 * Added less verbose casting for handles. Now instead of
       v8::Local<v8::String>::Cast(args[0])
   one can write
       args[0].As<v8::String>().

Review URL: http://codereview.chromium.org/660243

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4002 ce2b1a6d-e550-0410-aec6-3dcde31c8c00