Also add stability dependency only on maps that can transition,
and delay adding the dependencies until we are actually using
them, either in a HLoadNamedField or an HCheckMaps.

TEST=mjsunit/field-type-tracking
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/239923004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20796 ce2b1a6d-e550-0410-aec6-3dcde31c8c00