Noissue - Avoid loop if DevTools is closed

When DevTools is closed, the hit logger has no listeners. If we check this up front, we avoid the loop. This would be especially helpful in the case of requests from service workers.

[Manish Jethani, 2019-02-02 04:17:11]

Patch Set 1

See description.

[Sebastian Noack, 2019-02-02 05:13:59]

Is this optimization purely theoretical, or could you measure any difference in
performance?

Note that almost always there is only a single tabId (except for the
ServiceWorker scenario, and even then only if the user opened another tab
loading the same website controlled by a ServiceWorker, and even if that may
occasionally happen, it unlikely will be a lot of tabs).

[Manish Jethani, 2019-02-02 08:39:27]

On 2019/02/02 05:13:59, Sebastian Noack wrote:
> Is this optimization purely theoretical, or could you measure any difference
in
> performance?
> 
> Note that almost always there is only a single tabId (except for the
> ServiceWorker scenario, and even then only if the user opened another tab
> loading the same website controlled by a ServiceWorker, and even if that may
> occasionally happen, it unlikely will be a lot of tabs).

OK, I checked. It does help, but only very negligibly (you can only tell if you
look at the profiler data). I don't think it's worth it, I'll close this.