This feature makes it possible to associate data with a script and get it back
when the script is compiled or when an event is handled. It was historically
used by Chromium Dev Tools, but not any more. It is not used by node.js.

Note: this has nothing to do with the preparse data, despite the confusing name.
The preparse data is passed as ScriptData*.

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/184403002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19616 ce2b1a6d-e550-0410-aec6-3dcde31c8c00