callback load (or keyed load) IC.

The problem was that the IC code calls a stub, which can allocate and
thus trigger a GC if the stub is not already generated.  Problem is
solved by adding the ability to "try" to call a stub, trying to
generate the stub code if necessary but signaling an allocation
failure if generating the code is not possible.

Review URL: http://codereview.chromium.org/472002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3440 ce2b1a6d-e550-0410-aec6-3dcde31c8c00