strings, sliced strings, and changes to some object property representations.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/26034002

Patch from David Pacheco <dap@joyent.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17194 ce2b1a6d-e550-0410-aec6-3dcde31c8c00