Fix two bugs in the code compaction:

Fix two bugs in the code compaction:

1) Ensure that pc_to_code cache can iterate heap in the middle of compaction.

2) Increase precision of code target patching write-barrier. We shoould never record reloc slots on white objects because they might die and evacuation will overwrite their contents invalidating collected reloc slots as their positions are not aligned in the code stream.

3) remove bogus assertion.

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

Committed: http://code.google.com/p/v8/source/detail?r=9216

[Erik Corry, 2011-09-10 13:40:35]

LGTM