Mark some of the places we leave V8 via callbacks as transitions to...

Mark some of the places we leave V8 via callbacks as transitions to
state EXTERNAL rather than OTHER.

Committed: http://code.google.com/p/v8/source/detail?r=1632

[Kevin Millikin (Chromium), 2009-03-27 12:14:23]

Begin to handle EXTERNAL (outside V8) states separately from OTHER (in V8 but
not in JS, GC, or COMPILER).

With this change, it is possible to get into the EXTERNAL state via a callback
out of the VM, and not be able to get back in through the API.  That is
expected.  It can only happen when V8 is built with ENABLE_HEAP_PROTECTION and
run with --protect-heap.

[Mads Ager (chromium), 2009-03-27 12:18:47]

LGTM