Upgrade event emitter

[jasonLaster]

Summary of Changes

• We should try and upgrade the devtools-connection event emitter so that we are consistent w/ m-c.
• This patch has some release candidate versions, but does mostly work with the debugger. Some of the version numbers are wonky because i was working on an old branch and re-did a bunch of the devtools-environment work... oops 🤷‍♂️

What Doesn't Work

For some reason, client.fetchWorkers does not work. But if you comment it out everything seems to work fine

diff --git a/src/actions/debuggee.js b/src/actions/debuggee.js
index 6a52fae..a93ea2b 100644
--- a/src/actions/debuggee.js
+++ b/src/actions/debuggee.js
@@ -8,7 +8,7 @@ import type { Action, ThunkArgs } from "./types";

 export function updateWorkers() {
   return async function({ dispatch, client }: ThunkArgs) {
-    const { workers } = await client.fetchWorkers();
-    dispatch(({ type: "SET_WORKERS", workers }: Action));
+    // const { workers } = await client.fetchWorkers();
+    // dispatch(({ type: "SET_WORKERS", workers }: Action));
   };
 }
(END)

How to test

1. run yarn add -W [email protected]; yarn; in the debugger
2. run yarn start

everything should just work at this point. There might be other edge cases like fetchWorkers but i couldnt find them, and the mochitests will just work because they use mc.

[jasonLaster]

@wldcordeiro this will need some review, and we should make sure that it works in the debugger before landing