Fix several bugs in compaction:

Fix several bugs in compaction:

- when evicting evacuation candidates from free list create filler covering [top, limit) to ensure that page will remain iterable if it was iterable. this is important for Code space pages.

- we should not split typed slots between two slots buffers because we traverse them in opposite order.

- when recording reloc slot ensure that reloc host is not null before checking host's page flags.

R=erik.corry@gmail.com
BUG=
TEST=

Committed: http://code.google.com/p/v8/source/detail?r=9194

[Erik Corry, 2011-09-07 14:38:13]

LGTM