refactor: remove workaround for old Firefox

Author: web-padawan

packages/vaadin-radio-button/src/vaadin-radio-group.js

@@ -335,10 +335,8 @@ class RadioGroupElement extends ThemableMixin(DirMixin(PolymerElement)) {
 
     this.addEventListener('focusin', () => this._setFocused(this._containsFocus()));
 
-    // Need to check e.composed as a workaround for https://bugzilla.mozilla.org/show_bug.cgi?id=1472887
-    // otherwise FF runs validation on keyboard focus
-    this.addEventListener('focusout', (e) => {
-      e.composed && this.validate();
+    this.addEventListener('focusout', () => {
+      this.validate();
       this._setFocused(false);
     });
   }

packages/vaadin-radio-button/test/radio-group.test.js

@@ -499,12 +499,6 @@ describe('radio-group', () => {
       expect(group.invalid).to.be.true;
     });
 
-    it('should not validate on focusout when event is not composed', () => {
-      group.required = true;
-      focusout(group, false);
-      expect(group.invalid).to.be.false;
-    });
-
     it('should dispatch invalid-changed event when invalid changes', () => {
       const spy = sinon.spy();
       group.addEventListener('invalid-changed', spy);