Add map transition for observed objects
This patch enables objects to undergo a single transition when they become observed, avoiding the need to create a new map for every observed objects.
Observed objects which become unobserved does not cause another map transition and unobserved does not clear the observed bit on the map. The unobserved object.
R=verwaest@chromium.org
Review URL: https://codereview.chromium.org/
18221006
Patch from Rafael Weinstein <rafaelw@chromium.org>.
git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15650
ce2b1a6d-e550-0410-aec6-
3dcde31c8c00