added 260907 version of worker toolkit

worker-toolkit-flaredown/repo/frontend/app/mixins/back-navigateable.js

@@ -0,0 +1,23 @@
+import Ember from 'ember';
+
+const {
+  get,
+  Mixin,
+  inject: {
+    service,
+  },
+} = Ember;
+
+export default Mixin.create({
+  routeHistory: service(),
+
+  actions: {
+    navigateBack() {
+      const previous = get(this, 'routeHistory').popEntry();
+
+      if (previous) {
+        this.transitionToRoute(...previous);
+      }
+    },
+  },
+});