Property stores were not visited correctly by the visitor.
I fixed this issue by visiting property stores by visiting 
receiver and key directly (and not calling visit on the lhs property
 ast node)

Review URL: http://codereview.chromium.org/903003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4117 ce2b1a6d-e550-0410-aec6-3dcde31c8c00