Make TriggerEventWidgetComponent compatible with Ember 3.8

tests/dummy/app/components/trigger-event-widget.js

@@ -1,24 +1,26 @@
 import Component from '@glimmer/component';
-import { tracked } from '@glimmer/tracking';
+import { set } from '@ember/object';
 import { keyResponder, onKey } from 'ember-keyboard';
 
+// Use set(this) instead of tracked properties for Ember 3.8 compatibility.
 @keyResponder({ activated: true })
 export default class extends Component {
-  @tracked keyboardActivated = true;
-  @tracked keyDown = false;
-  @tracked keyDownWithMods = false;
-  @tracked keyPress = false;
-  @tracked keyUp = false;
+  keyboardActivated = true;
+  keyDown = false;
+  keyDownWithMods = false;
+  keyPress = false;
+  keyUp = false;
 
   @onKey('KeyA', { event: 'keydown' })
-  toggleKeyDown = () => (this.keyDown = !this.keyDown);
+  toggleKeyDown = () => set(this, 'keyDown', !this.keyDown);
 
   @onKey('KeyA+cmd+shift', { event: 'keydown' })
-  toggleKeyDownWithMods = () => (this.keyDownWithMods = !this.keyDownWithMods);
+  toggleKeyDownWithMods = () =>
+    set(this, 'keyDownWithMods', !this.keyDownWithMods);
 
   @onKey('KeyA', { event: 'keypress' })
-  toggleKeyPress = () => (this.keyPress = !this.keyPress);
+  toggleKeyPress = () => set(this, 'keyPress', !this.keyPress);
 
   @onKey('KeyA', { event: 'keyup' })
-  toggleKeyUp = () => (this.keyUp = !this.keyUp);
+  toggleKeyUp = () => set(this, 'keyUp', !this.keyUp);
 }