fix(nav): view.id is not overridden

fixes #8794

Author: manucorporat

src/navigation/nav-controller-base.ts

@@ -689,7 +689,10 @@ export class NavControllerBase extends Ion implements NavController {
       view._setNav(this);
 
       // give this inserted view an ID
-      view.id = this.id + '-' + (++this._ids);
+      this._ids++;
+      if (!view.id) {
+        view.id = `${this.id}-${this._ids}`;
+      }
 
       // insert the entering view into the correct index in the stack
       this._views.splice(index, 0, view);

src/navigation/test/nav-controller.spec.ts

@@ -165,6 +165,15 @@ describe('NavController', () => {
 
   describe('insert', () => {
 
+    it('should not modify the view id', () => {
+      let view = mockView(MockView4);
+      view.id = 'custom_id';
+      nav.insert(0, view);
+
+      expect(view.id).toEqual('custom_id');
+    });
+
+
     it('should insert at the begining with no async transition', () => {
       let view4 = mockView(MockView4);
       let instance4 = spyOnLifecycles(view4);