Parser cleanup: PreParser doesn't need to produce symbol data any more.

Parser cleanup: PreParser doesn't need to produce symbol data any more.

State of the art:
- Chromium doesn't do a separate preparsing phase any more.
- We start parsing with Parser, and when it sees a lazy function, it falls back
to PreParser for that function.
- The symbol data should contain symbols which are *outside* lazy functions.
- So Parser should always produce symbol data, and PreParser should never.
- Because it's this simple now, we don't need to keep track of "should
produce symbol data" (i.e., whether we're inside a lazy func or not).

R=ulan@chromium.org
BUG=

Review URL: https://codereview.chromium.org/222123003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20707 ce2b1a6d-e550-0410-aec6-3dcde31c8c00