Allow users of the V8 API to distinguish between unset and undefined HiddenValues

BUG=v8:2746
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/17781002

Patch from Adam Klein <adamk@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15329 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove useless ZoneScopes from Parser.

R=danno@chromium.org
BUG=

Review URL: https://codereview.chromium.org/17817003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15330 ce2b1a6d-e550-0410-aec6-3dcde31c8c00