fix(radio): select only one radio when w/out ngModel

Closes #5659

ionic/components/radio/radio-group.ts

@@ -125,6 +125,7 @@ export class RadioGroup {
   registerOnChange(fn: Function): void {
     this._fn = fn;
     this.onChange = (val: any) => {
+      // onChange used when there's an ngControl
       console.debug('radio group, onChange', val);
       fn(val);
       this.value = val;
@@ -206,7 +207,14 @@ export class RadioGroup {
   /**
    * @private
    */
-  onChange(_) {}
+  onChange(val: any) {
+    // onChange used when there is not an ngControl
+    console.debug('radio group, onChange w/out ngControl', val);
+    this.value = val;
+    this._update();
+    this.onTouched();
+    this.change.emit(val);
+  }
 
   /**
    * @private

ionic/components/radio/test/basic/index.ts

@@ -13,7 +13,6 @@ class E2EApp {
   currencies: Array<string>;
   items: Array<{description: string, value: any}>;
   relationship: string;
-  pet: string;
   selectedTime: number = 60;
 
   constructor() {

ionic/components/radio/test/basic/main.html

@@ -80,7 +80,7 @@
     <code><b>relationship:</b> {{relationship}}</code>
   </div>
 
-  <div radio-group [(ngModel)]="pet" (change)="petChange($event)">
+  <div radio-group (change)="petChange($event)">
     <p>
       <ion-radio (select)="dogSelect($event)"></ion-radio>
       Dogs
@@ -95,10 +95,6 @@
     </p>
   </div>
 
-  <div padding>
-    <code><b>pet:</b> {{pet}}</code>
-  </div>
-
   <ion-list radio-group [(ngModel)]="someValue">
     <ion-item *ngFor="#item of items">
       <ion-label>