Once we crankshaft a method, we should turn off allocation site info for
constructed arrays. Additionally, the semantics for doing this were
awkward because the constructed array code stubs get an
AllocationSiteMode as a minor key, but it's used as a permission to
determine the final mode locally based on ElementsKind. I refactored
this to a simpler boolean for override or local control.

BUG=
R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/16206007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14934 ce2b1a6d-e550-0410-aec6-3dcde31c8c00