This fixes a corner-case where a frozen prototype with existing hidden
properties might prevent setting hidden properties on another object.

R=rossberg@chromium.org
BUG=v8:2829

Review URL: https://codereview.chromium.org/22799021

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16276 ce2b1a6d-e550-0410-aec6-3dcde31c8c00