debugger: call `this.resume()` after `this.run()`

Checklist

• make -j8 test (UNIX), or vcbuild test nosign (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

debugger

Description of change

This addresses https://github.com/nodejs/node/issues/9854

The issue was introduced here and first appeared in 6.2.2.

I haven't figured out the best way to test this yet. Apparently, existing tests didn't catch the regression though.