Save zone memory in LEnvironment by using a bit vector.
Save zone memory in LEnvironment by using a bit vector.

We don't need to store the full representation for each value. Instead
a bit to indicate tagged/untagged is enough.
Review URL: http://codereview.chromium.org/9104042

git-svn-id: b158db1e4b4ab85d4c9e510fdef4b1e8c614b15b@10572 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh