fix(radio): ng-touched incorrectly being set on click (#12560)

* The `ControlValueAccessor` `onTouched` should be just called if a radio-button blurred. Right now, the `ng-touched` state will be immediately set if someone presses SPACE or clicks on a radio-button.

Author: devversion

src/lib/radio/radio.spec.ts

@@ -456,6 +456,14 @@ describe('MatRadio', () => {
       radioLabelElements[2].click();
       fixture.detectChanges();
 
+      expect(groupNgModel.valid).toBe(true);
+      expect(groupNgModel.pristine).toBe(false);
+      expect(groupNgModel.touched).toBe(false);
+
+      // Blur the input element in order to verify that the ng-touched state has been set to true.
+      // The touched state should be only set to true after the form control has been blurred.
+      dispatchFakeEvent(innerRadios[2].nativeElement, 'blur');
+
       expect(groupNgModel.valid).toBe(true);
       expect(groupNgModel.pristine).toBe(false);
       expect(groupNgModel.touched).toBe(true);

src/lib/radio/radio.ts

@@ -553,7 +553,6 @@ export class MatRadioButton extends _MatRadioButtonMixinBase
 
     if (this.radioGroup) {
       this.radioGroup._controlValueAccessorChangeFn(this.value);
-      this.radioGroup._touch();
       if (groupValueChanged) {
         this.radioGroup._emitChangeEvent();
       }