In order to address bug 1614291, we have to start listening for every resource, like console messages, network requests, page error, ... via the Resources API.
The Resources API will allow to listen for these resources earlier than the current setup where we use the TargetList to listen to new target, and request to listen after the target is created.
With the Resources API, we will know as early as the document starts loading that we have to start listening for something.

This bug is about focusing on only one usecase in DevTools. And only one usecase in the console: the console messages.

This demonstrates using the Resources API for the console messages,
using the existing actor methods. It helps proving that this will work against old runtimes.
But the plan is to followup in bug 1620243 so that we implement this code on the server side.
This will help getting rid of this LegacyImplementation code and have a simplier code on the server.

Tracking Fission DevTools bugs for Fission Nightly (M6) milestone

Try run with the new name ResourceWatcher
https://treeherder.mozilla.org/#/jobs?repo=try&revision=918129a2777d6d9ea99b7c34d970e2f2511c2c01

https://hg.mozilla.org/mozilla-central/rev/d0732ef79150