This avoids e.g. trying to disassemble those parts, which could result
in failed assertions.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/201613005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19992 ce2b1a6d-e550-0410-aec6-3dcde31c8c00