It is a type error to treat a flag (an enum) as if it were a flag mask (an
int derived from shifting a bit by the enum value).  It is error prone to
have functions that take flag mask arguments because they will silently
accept flags.

Review URL: http://codereview.chromium.org/6373011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6500 ce2b1a6d-e550-0410-aec6-3dcde31c8c00