Port r11306 (36b58f7).

Original commit message:

This passes the isolate through to API callback functions so that it is
available through AccessorInfo and Arguments. This allows bindings to
avoid unnecessary TLS lookups to retrieve the current isolate.

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10083001
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11319 ce2b1a6d-e550-0410-aec6-3dcde31c8c00