Preparsing is always maximally lazy (every function that can be lazy is preparsed
lazily), but Parser has more complicated laziness logic.

If we're going to parse eagerly, and we have preparse data from lazy preparsing,
we're gonna have a bad time. The symbol stream won't contain symbols inside lazy
functions, and when the Parser parses them eagerly, it will consume symbols from
the symbol stream, and everything will go wrong.

This bug was hidden because the symbol cache was not used for real (see
https://codereview.chromium.org/172753002/ ).

R=ulan@chromium.org
BUG=346207
LOG=Y

Review URL: https://codereview.chromium.org/177973002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19532 ce2b1a6d-e550-0410-aec6-3dcde31c8c00