Description:
Turn message property of the error object into a data property.

R=svenpa...@chromium.org
BUG=

Please review this at https://chromiumcodereview.appspot.com/11368142/

SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge

This change includes:

- Format the message string when the error object is constructed, instead of
doing it lazily. Performance impact should be low.
- Turn the message dictionary into a object literal.
- Pass message type and formatting arguments as string and array instead of
bundled into a JSMessageObject. This makes some runtime calls to extract the
values obsolete.
- A bug discovered in proxies.js has been filed in v8:2398

http://codereview.chromium.org/11368142/diff/1/src/messages.cc
File src/messages.cc (right):

http://codereview.chromium.org/11368142/diff/1/src/messages.cc#newcod...
src/messages.cc:158: ASSERT(data->IsJSMessageObject());
No need for this ASSERT, all cast methods do this implicitly.