fix(language-service): infer context type of structural directives (#35537) (#35561)

PR Close #35561

packages/language-service/test/project/app/main.ts

@@ -43,6 +43,7 @@ import * as ParsingCases from './parsing-cases';
     ParsingCases.StringModel,
     ParsingCases.TemplateReference,
     ParsingCases.TestComponent,
+    ParsingCases.WithContextDirective,
   ]
 })
 export class AppModule {

packages/language-service/test/project/app/parsing-cases.ts

@@ -127,6 +127,21 @@ export class CounterDirective implements OnChanges {
   }
 }
 
+interface WithContextDirectiveContext {
+  $implicit: {implicitPerson: Person;};
+  nonImplicitPerson: Person;
+}
+
+@Directive({selector: '[withContext]'})
+export class WithContextDirective {
+  constructor(_template: TemplateRef<WithContextDirectiveContext>) {}
+
+  static ngTemplateContextGuard(dir: WithContextDirective, ctx: unknown):
+      ctx is WithContextDirectiveContext {
+    return true;
+  }
+}
+
 /**
  * This Component provides the `test-comp` selector.
  */