New Compilation API, part 1, try 2

New Compilation API, part 1, try 2

- Distinguish between context bound scripts (Script) and context unbound scripts
(UnboundScript).
- Add ScriptCompiler (which will later contain functions for async compilation).

This is a breaking change, in particular, Script::New no longer exists (it is
replaced by ScriptCompiler::CompileUnbound). Script::Compile remains as a
backwards-compatible shorthand for ScriptCompiler::Compile.

Passing CompilerOptions with produce_data_to_cache = true doesn't do anything
yet; the only way to generate the data to cache is the old preparsing API. (To
be fixed in the next version.)

This is a fixed version of https://codereview.chromium.org/186723005/

BUG=
R=dcarney@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19925

[dcarney, 2014-03-13 18:30:39]

lgtm

[marja, 2014-03-14 10:20:48]

Committed patchset #1 manually as r19925 (presubmit successful).