Fix concurrent osr.

Fix concurrent osr.

InstallOptimizedCode aquires ownership on the compilation info and deletes
it on return, tearing down the attached zone.  The OptimizingCompiler
object is a zone object allocated in just that zone, so it also gets
deleted.  Effectively, InstallOptimizedCode cleans up when it's done, so
the OptimizingCompiler object it receives is invalidated afterwards.

R=titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/23769007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16609 ce2b1a6d-e550-0410-aec6-3dcde31c8c00