This is a regression relative to the original behavior, when "native" was a keyword,
since keywords cannot contain esacpes.

Added tests for escapes and for not allowing line-terminators betwen "native" and "function".

Review URL: http://codereview.chromium.org/7206022

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8327 ce2b1a6d-e550-0410-aec6-3dcde31c8c00