debug info at places where the debugger can't stop.
This fixes the ARM version after
http://codereview.chromium.org/14170
Reformat debug-backtrace.js test.
Review URL: http://codereview.chromium.org/155285

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2416 ce2b1a6d-e550-0410-aec6-3dcde31c8c00