This introduces a global weak hash table that maps objects embedded in
optimized code to dependent code lists. Using this table we can deoptimize
optimized code whenever a weak object embedded in the code dies.

BUG=v8:2073
R=hpayer@chromium.org, mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/23477061

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17102 ce2b1a6d-e550-0410-aec6-3dcde31c8c00