Reapply r1900, r1897, r1895 with a fix....

Reapply r1900, r1897, r1895 with a fix.

When a paged space shrinks by an even multiple of the chunk size,
ensure that the cached last page in the space is updated.


Committed: http://code.google.com/p/v8/source/detail?r=1944

[Kevin Millikin (Chromium), 2009-05-12 14:48:35]

The bugfix is spaces.cc:734.

[Erik Corry, 2009-05-13 10:56:29]

I think the places where we access the last page variable we should (in debug
mode) traverse the pages and assert that the last page is the one stored in the
variable.

Otherwise LGTM.