Update tests to use the new compilation API + related fixes.

Esp. get rid of PreCompile in tests, as it's going to be removed.

Notes:
- The new compilation API doesn't have a separate precompilation phase, so there
is no separate way to check for errors except checking the compilation
errors. Removed some tests which don't make sense any more.
- test-api/Regress31661 didn't make sense as a regression test even before the
compilation API changes, because Blink doesn't precompile this short scripts. So
detecting this kind of errors (see crbug.com/31661 for more information) cannot rely
on precompilation errors.
- test-parsing/PreParserStrictOctal has nothing to do with PreParser, and the comment
about "forcing preparsing" was just wrong.
- test-api/PreCompile was supposed to test that "pre-compilation (aka
preparsing) can be called without initializing the whole VM"; that's no longer
true, since there's no separate precompilation step in the new compile
API. There are other tests (test-parsing/DontRegressPreParserDataSizes) which
ensure that we produce cached data.
- Updated tests which test preparsing to use PreParser directly (not via the
 preparsing API).
- In the new compilation API, the user doesn't need to deal with ScriptData
ever. It's only used internally, and needed in tests that test internal aspects
(e.g., modify the cached data before passing it back).
- Some tests which used to test preparse + parse now test first time parse +
  second time parse, and had to be modified to ensure we don't hit the
  compilation cache.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/225743002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20511 ce2b1a6d-e550-0410-aec6-3dcde31c8c00