Mark the empty script object, the script for the empty function and the D8 utility script as native scripts.

This is mainly to avoid these scripts showing up in the debugger when showing normal scripts.

Removed the check for the empty script in the debugger function returning loaded scripts as this check only filtered out the empty script from the debugger context and not empty scripts in all other contexts. Also this filter did not take the script for the empty function into account.
Review URL: http://codereview.chromium.org/39322

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1443 ce2b1a6d-e550-0410-aec6-3dcde31c8c00