Convert the code to be similar with JS version. Recursive traversal is dangerous as it can cause stack exhaustion on deep trees.

Review URL: http://codereview.chromium.org/211024

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2939 ce2b1a6d-e550-0410-aec6-3dcde31c8c00