Remove bogus assertion in parallel recompilation.

Functions that are optimized by the parallel thread and ready for installing
are not necessarily marked as in-recompilation-queue. For example, OSR could
have replaced the code by optimized code.

R=hpayer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/18769003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15544 ce2b1a6d-e550-0410-aec6-3dcde31c8c00