Allow inlining of multiple closures from shared function.

This allows Crankshaft to allow inlining of multiple different closures
that were all derived from the same shared function info. This pattern
appears when libraries provide generic closures that are used over and
over again at different call-sites.

R=jkummerow@chromium.org
TEST=mjsunit/compiler/inline-closures

Review URL: https://codereview.chromium.org/12071002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13522 ce2b1a6d-e550-0410-aec6-3dcde31c8c00