If the runtime is taken for a constructor like "new Array(100000)", where
allocation site info already led to an elements kind of DOUBLE, then the runtime
would fail to transition the array to dictionary mode. Better to recognize this
case and avoid wasting time by following the advice. Furthermore, it offers a
way to recognize that the array should be in dictionary mode (though a future
checkin will capitalize on that).

BUG=
R=danno@chromium.org

Review URL: https://codereview.chromium.org/15993012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14966 ce2b1a6d-e550-0410-aec6-3dcde31c8c00