feat(ivy): support for the ngForOf directive, with tests (#21430)

Implement NgOnChangesFeature, ViewContainerRef, TemplateRef,
and the renderEmbeddedTemplate instruction, and wire together the
pieces required for the ngForOf directive to work.

PR Close #21430

packages/core/src/render3/interfaces/container.ts

@@ -66,6 +66,13 @@ export interface LContainer {
    * The template extracted from the location of the Container.
    */
   readonly template: ComponentTemplate<any>|null;
+
+
+  /**
+   * A count of dynamic views rendered into this container. If this is non-zero, the `views` array
+   * will be traversed when refreshing dynamic views on this container.
+   */
+  dynamicViewCount: number;
 }
 
 /**

packages/core/src/render3/interfaces/definition.ts

@@ -16,7 +16,6 @@ import {resolveRendererType2} from '../../view/util';
 export type ComponentTemplate<T> = {
   (ctx: T, creationMode: boolean): void; ngPrivateData?: never;
 };
-export type EmbeddedTemplate<T> = (ctx: T) => void;
 
 export interface ComponentType<T> extends Type<T> { ngComponentDef: ComponentDef<T>; }
 

packages/core/src/render3/interfaces/view.ts

@@ -7,7 +7,7 @@
  */
 
 import {LContainer} from './container';
-import {DirectiveDef} from './definition';
+import {ComponentTemplate, DirectiveDef} from './definition';
 import {LElementNode, LViewNode, TNode} from './node';
 import {Renderer3} from './renderer';
 
@@ -138,6 +138,24 @@ export interface LView {
    * directive defs are stored).
    */
   tView: TView;
+
+  /**
+   * For dynamically inserted views, the template function to refresh the view.
+   */
+  template: ComponentTemplate<{}>|null;
+
+  /**
+   * For embedded views, the context with which to render the template.
+   */
+  context: {}|null;
+
+  /**
+   * A count of dynamic views that are children of this view (indirectly via containers).
+   *
+   * This is used to decide whether to scan children of this view when refreshing dynamic views
+   * after refreshing the view itself.
+   */
+  dynamicViewCount: number;
 }
 
 /** Interface necessary to work with view tree traversal */