with AST IDs. Previously 3 different places had to match in how they handle a
given case, now we are down to 2, with an even simpler logic.

The downside is that due to this simpler logic the allocated dictionary could be
larger than before, but test have shown that this happens *very* rarely, because
its capacity is rounded to the next power of 2, anyway. Furthermore, the oracle
doesn't live long enough that we should really care.

The whole oracle is probably still a bit too tricky in its details, but this is
at least a step into the right direction.
Review URL: http://codereview.chromium.org/7204003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8330 ce2b1a6d-e550-0410-aec6-3dcde31c8c00