Partially revert r9734 due to crashes in dev and canary channel.

This reverts the changes to the ScopeIterator from r9734 to the
previous implementation. The other changes in the commit to Parser,
Scope and (Serialized)ScopeInfo are retained.

BUG=104522,v8:1824,v8:1826

Review URL: http://codereview.chromium.org/8547007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10033 ce2b1a6d-e550-0410-aec6-3dcde31c8c00