fix(PageRouterOutlet): Don't remove grandchild views when moving component

PageRouterOutlet.loadComponentInPage moves the componentView from its native parent,
to the Page. Don't remove the componentView's children when it is removed from the
native parent.

Author: m-abs

Diff for: nativescript-angular/router/page-router-outlet.ts

@@ -357,7 +357,7 @@ export class PageRouterOutlet implements OnDestroy { // tslint:disable-line:dire
         // Component loaded. Find its root native view.
         const componentView = componentRef.location.nativeElement;
         // Remove it from original native parent.
-        this.viewUtil.removeChild(componentView.parent, componentView);
+        this.viewUtil.removeChild(componentView.parent, componentView, false);
         // Add it to the new page
         this.viewUtil.insertChild(page, componentView);
 

Diff for: nativescript-angular/view-util.ts

@@ -157,9 +157,10 @@ export class ViewUtil {
         return next;
     }
 
-    public removeChild(parent: View, child: View) {
+    public removeChild(parent: View, child: View, removeGrandchildren = true) {
         if (isLogEnabled()) {
-           traceLog(`ViewUtil.removeChild parent: ${parent} child: ${child}`);
+           traceLog(`ViewUtil.removeChild parent: ${parent} child: ${child} `
+            + `remove grandchildren: ${removeGrandchildren}`);
         }
 
         if (!parent) {
@@ -170,7 +171,8 @@ export class ViewUtil {
         const extendedChild = this.ensureNgViewExtensions(child);
 
         // Remove the child's children and their children
-        while (extendedChild && extendedChild.firstChild) {
+        // Unless called from PageRouterOutlet when the child is moved from once parent to another.
+        while (extendedChild && extendedChild.firstChild && removeGrandchildren) {
             const grandchild = extendedChild.firstChild;
             if (isLogEnabled()) {
                 traceLog(`ViewUtil.removeChild parent: ${parent} child: ${extendedChild} grandchild: ${grandchild}`);