If the top optimized code in call stack is at the point that does not support
deoptimization, then treat the maps in the code as strong pointers.

Note that other optimized code in call stack must support deoptimization
because of the call instruction with side-effects.

BUG=217858,v8:2073
R=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/16955008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15452 ce2b1a6d-e550-0410-aec6-3dcde31c8c00