immediately if holder has this property or saves binary search on holder if
property doesn't belong to holder.  Of course, in the cases when named getter
returns nothing.

That gives ~20% for dom benchmark/Document Object String Get, speeds up overall
dom_perf (not dramatically) and overall score for peacekeeper.  Strange, but DOM
part of peacekeepr runs somewhat slower.
Review URL: http://codereview.chromium.org/118118

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2093 ce2b1a6d-e550-0410-aec6-3dcde31c8c00