Only make function literals in top-level object literals pretenured and constant function propert...

Only make function literals in top-level object literals pretenured and constant function properties.

This change is a refinement of http://code.google.com/p/v8/source/detail?r=7283. Making all
function literals inside object literals constant function properties causes us to lose map
sharing. This hurts code where many object literals are created.

The idea is that top-level code is mostly executed once and functions inside top-level
object literals remain fast with this change.

BUG=v8:1795
Committed: http://code.google.com/p/v8/source/detail?r=10096

[Vyacheslav Egorov (Chromium), 2011-11-30 15:02:59]

lgtm