Removed a related TODO in d8.cc on the way.

BUG=v8::3318
LOG=y
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/275463002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21195 ce2b1a6d-e550-0410-aec6-3dcde31c8c00