Bug 1574830 - Scanning should not show an overlay. r=bhackett

Differential Revision: https://phabricator.services.mozilla.com/D42443

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

devtools/server/actors/thread.js

@@ -441,6 +441,12 @@ const ThreadActor = ActorClassWithSpec(threadSpec, {
       this.pauseOverlay
     ) {
       const reason = this._priorPause.why.type;
+
+      // Do not show the pause overlay when scanning
+      if (this.dbg.replaying) {
+        return;
+      }
+
       this.pauseOverlay.show(null, { reason });
     }
   },