Parser cleanup: less member variables.

Parser had unnecessary member pointers to stuff stored in the
CompilationInfo (which Parser also points to).

As we add more parsing code paths (in particular, script streaming), this gets
confusing and Parser and CompilationInfo can get out of sync.

BUG=
R=jochen@chromium.org, rossberg@chromium.org

Review URL: https://codereview.chromium.org/527233003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23861 ce2b1a6d-e550-0410-aec6-3dcde31c8c00