1418, and 1419 from bleeding_edge, reverted in 1429.
* Fix of $1 accessor on sliced strings.
* Fix of lastParen method when last parenthesis did not match.
Review URL: http://codereview.chromium.org/43075

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1491 ce2b1a6d-e550-0410-aec6-3dcde31c8c00