Set the security token on the debugger context after all contexts have
been created in d8.  This ensures that all d8 contexts (including the
debugger context) can access eachother.

Copy extra command-line handling from the shell sample to d8.

Review URL: http://codereview.chromium.org/12431

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@836 ce2b1a6d-e550-0410-aec6-3dcde31c8c00