Add regression tests for PrePreparser.

These tests ensure that PreParser doesn't start producing less data when it's
getting refactored.

BUG=3126
LOG=N
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/157373002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19192 ce2b1a6d-e550-0410-aec6-3dcde31c8c00