Misc cleanup (split from the "delay string / value internalization" CL).

- Missing includes / forward declaration
- Parser: Simplifying calling error reporting funcs.

R=ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/307393002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21652 ce2b1a6d-e550-0410-aec6-3dcde31c8c00