Using isNaN() here is bogus because it performs an implicit toNumber()
conversion, hence something like assertSame(undefined, {}) would not
throw an exception. These are not the NaNs you are looking for.

R=rossberg@chromium.org
TEST=mjsunit

Review URL: http://codereview.chromium.org/8400056

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9831 ce2b1a6d-e550-0410-aec6-3dcde31c8c00