The LookupResult utility class is used in handlified code, but it can
contain a raw pointer to the lookup's holder object.  Create a per-thread
stack of live LookupResults and iterate all the live ones on GC.

R=vegorov@chromium.org,erik.corry@gmail.com
BUG=
TEST=

Review URL: http://codereview.chromium.org/8341009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9676 ce2b1a6d-e550-0410-aec6-3dcde31c8c00