Bug 1573780 - add targetFront to deprecated debugger client; r=jlast

Differential Revision: https://phabricator.services.mozilla.com/D42497

--HG--
extra : moz-landing-system : lando

devtools/shared/client/deprecated-thread-client.js

@@ -37,6 +37,7 @@ function ThreadClient(client, actor) {
   this._actor = actor;
   this._pauseGrips = {};
   this._threadGrips = {};
+  this.targetFront = null;
   this.request = this.client.request;
 }
 
@@ -235,6 +236,7 @@ ThreadClient.prototype = {
   }),
 
   destroy: function() {
+    this.targetFront = null;
     return this.detach();
   },
 

devtools/shared/fronts/targets/target-mixin.js

@@ -417,6 +417,7 @@ function TargetMixin(parentClass) {
         this.threadFront = new ThreadClient(this._client, this._threadActor);
         this.fronts.set("thread", this.threadFront);
         this.threadFront.actorID = this._threadActor;
+        this.threadFront.targetFront = this;
         this.manage(this.threadFront);
       }
       const result = await this.threadFront.attach(options);