Diffs and retaining paths are implemented on JS side. There is no need
to maintain native implementation.

R=vitalyr@chromium.org
BUG=none
TEST=none

Review URL: http://codereview.chromium.org/6770009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7412 ce2b1a6d-e550-0410-aec6-3dcde31c8c00