The motivation is that by only entering the debugger scope to call into
the debug context should not cause code to be compiled for debugging.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/306563002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21645 ce2b1a6d-e550-0410-aec6-3dcde31c8c00