Date set methods (setMinutes, setHours, etc.) should return the time value as a number instead of JSDate.

R=jkummerow@chromium.org
TEST=test/mjsunit/regress/regress-2027.js

Review URL: https://chromiumcodereview.appspot.com/9809010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11140 ce2b1a6d-e550-0410-aec6-3dcde31c8c00