Moving logic to AstNode to determine how many type cells are required.

With this change, we'll be able to discover how many type cells we
need at parse time, enabling future optimizations.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/141533004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18668 ce2b1a6d-e550-0410-aec6-3dcde31c8c00