Fix Array.length, String.length and Function.prototype LoadICs on x64.

R=jkummerow@chromium.org
BUG=v8:2568

Review URL: https://chromiumcodereview.appspot.com/12545004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13847 ce2b1a6d-e550-0410-aec6-3dcde31c8c00