Fix PathTracer.

When tracing, we abuse the map for marking, thereby mutating it.
HeapObject::map() takes care of recovering unabused value.

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/316533002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21626 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix compilation on win shared and mips

TBR=mvstanton@chromium.org
LOG=n
BUG=none

Review URL: https://codereview.chromium.org/309983002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21627 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix test

R=bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/306353002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21628 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Rename new_space_dominator to dominator since dominators can also be in old space.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/312713002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21629 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Improve write barriers in optimized code.

Use a cheaper RecordWriteForMap() to update the
write barrier for maps. And skip the value check
in RecordWriteField() when we statically know that
the value is in new space (and therefore has "pointers
to here are interesting" flag set).

R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/297763006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21630 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
PPC: upstream changes [3c8e51ae982d639ad8a7dfffe936d18d885162a2]