debugger: fixed bug in breakpoint regex escaping.

Fixed a bug in setBreakpoint() where not all regex characters were
escaped while constructing scriptRegEx for V8.

See also commits

- bajtos/node@7d68aa23333917a48fc26f99cfb8a148a457a679
- joyent/node@5db936d2aecaddb5d539855a150813e36df45b66