The previous behavior, which caused Array.prototype.unshift() (with no args)
to have side-effects, no longer matches the spec (ES6 changed the no-arg behavior
in April 2014). The new SmartMove behavior is also compatible with current
versions of Firefox.

This is a baby step towards getting rid of SmartMove; it isolates the test
change in this patch, instead of lumping it in confusingly with all the
other test updates necessary for moving away from SmartMove.

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/666883009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24854 ce2b1a6d-e550-0410-aec6-3dcde31c8c00