Merged r13361, r13481 into 3.15 branch.

Fix shared function info code replacement.

Fix corner case when JSFunction is evicted from flusher.

R=hpayer@chromium.org
BUG=chromium:169209,chromium:168801
TEST=cctest/test-heap

Review URL: https://codereview.chromium.org/12084062

git-svn-id: https://v8.googlecode.com/svn/branches/3.15@13555 ce2b1a6d-e550-0410-aec6-3dcde31c8c00