Eliminate the constant location used for literals in the AST.

Eliminate the constant location used for literals in the AST.
Literals now have a location of temporary by default and are
responsible for moving themselves into their location like all other
expressions.

The constant location turned out not to allow us to avoid checking
subexpressions in AST interior nodes, and it turned out to require
checking after some normal calls to Visit (like for the arguments to a
call).  With this change do not have to check after a call to Visit
that we got our result in the expected location.

Review URL: http://codereview.chromium.org/339004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3137 ce2b1a6d-e550-0410-aec6-3dcde31c8c00