fix(cdk/scrolling): adds ngTemplateContextGuard (angular#27276)

BREAKING CHANGE:
* Virtual scrolling lists now have proper type checking which can reveal some previously-hidden compilation errors.

* fix(cdk/scrolling): adds ngTemplateContextGuard

implements ngTemplateContextGuard for CdkVirtualForOf directive

fixes angular#26609

* fixup! fix(cdk/scrolling): adds ngTemplateContextGuard

Author: naaajii

src/cdk/scrolling/virtual-for-of.ts

@@ -395,4 +395,11 @@ export class CdkVirtualForOf<T>
       index,
     };
   }
+
+  static ngTemplateContextGuard<T>(
+    directive: CdkVirtualForOf<T>,
+    context: unknown,
+  ): context is CdkVirtualForOfContext<T> {
+    return true;
+  }
 }

tools/public_api_guard/cdk/scrolling.md

@@ -120,6 +120,8 @@ export class CdkVirtualForOf<T> implements CdkVirtualScrollRepeater<T>, Collecti
     ngDoCheck(): void;
     // (undocumented)
     ngOnDestroy(): void;
+    // (undocumented)
+    static ngTemplateContextGuard<T>(directive: CdkVirtualForOf<T>, context: unknown): context is CdkVirtualForOfContext<T>;
     readonly viewChange: Subject<ListRange>;
     // (undocumented)
     static ɵdir: i0.ɵɵDirectiveDeclaration<CdkVirtualForOf<any>, "[cdkVirtualFor][cdkVirtualForOf]", never, { "cdkVirtualForOf": { "alias": "cdkVirtualForOf"; "required": false; }; "cdkVirtualForTrackBy": { "alias": "cdkVirtualForTrackBy"; "required": false; }; "cdkVirtualForTemplate": { "alias": "cdkVirtualForTemplate"; "required": false; }; "cdkVirtualForTemplateCacheSize": { "alias": "cdkVirtualForTemplateCacheSize"; "required": false; }; }, {}, never, never, true, never>;