Fixed
1) Missing line in x64 port.
2) GcStress found a logic error in the IC miss handler.

R=verwaest@chromium.org

Review URL: https://codereview.chromium.org/224903005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20516 ce2b1a6d-e550-0410-aec6-3dcde31c8c00