The predicate CanBeSpilled had a bug, prohibiting the necessary spilling and
correct splitting of live ranges. Removed a redundant assertion immediately done
by the callee anyway.

Thanks to Slava for help with that issue and the entertaining historical
background of the whole story... ;-)

BUG=177883

Review URL: https://codereview.chromium.org/12631012

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13891 ce2b1a6d-e550-0410-aec6-3dcde31c8c00