DEV: allows this.get in widgets (#8571)

app/assets/javascripts/discourse/widgets/widget.js.es6

@@ -12,6 +12,7 @@ import { h } from "virtual-dom";
 import DecoratorHelper from "discourse/widgets/decorator-helper";
 import { Promise } from "rsvp";
 import ENV from "discourse-common/config/environment";
+import { get } from "@ember/object";
 
 const _registry = {};
 
@@ -150,6 +151,10 @@ export default class Widget {
 
   destroy() {}
 
+  get(propertyPath) {
+    return get(this, propertyPath);
+  }
+
   render(prev) {
     const { dirtyKeys } = this;