Debugger should not stop in its own code and in code of built-in functions since it may confuse user.Debug break handler checks whether current function is a built-in or a debugger one and just resumes execution if it is.

CallCheckStackGuardState is no longer called in loop in the RegExp code as it hangs if debug break flag is not reset after calling Execution::HandleStackGuardInterrupt.
Review URL: http://codereview.chromium.org/160001

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2531 ce2b1a6d-e550-0410-aec6-3dcde31c8c00