methods rely on the time values passed in being within a certain range
- not significantly larger than the the ECMA 262 specified time
range. When creating a time, always make it NaN if there is no way
that it can be within range even after UTC conversion.

Review URL: http://codereview.chromium.org/5905003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6048 ce2b1a6d-e550-0410-aec6-3dcde31c8c00