Probe number dictionaries in generated code on ia32.

Probe number dictionaries in generated code on ia32.

With my previous change to limit memory for object literals, we get more slow-case elements and this makes up for the slowdown when loading from those slow-case elements.

The most complicated part here is the computation of the integer hash code.  We might want to simplify the integer hash function.
Review URL: http://codereview.chromium.org/857003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4109 ce2b1a6d-e550-0410-aec6-3dcde31c8c00