Move Promise tracking from debug to isolate.

This prepares for tracking promise rejections when debugger is off.

R=aandrey@chromium.org

Review URL: https://codereview.chromium.org/462413003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23101 ce2b1a6d-e550-0410-aec6-3dcde31c8c00