Rename Literal::handle to Literal::value

Just a completely mechanical change...

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/17576005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15280 ce2b1a6d-e550-0410-aec6-3dcde31c8c00