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*.

Note 2: This is the same as r19616 ( https://codereview.chromium.org/184403002/ )
with a unused variable fix in bootstrapper.cc.

R=svenpanne@chromium.org
BUG=

Review URL: https://codereview.chromium.org/185533014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19702 ce2b1a6d-e550-0410-aec6-3dcde31c8c00