refactor(compiler-cli): remove unnecessary constraint on `isDeclarationReference()` (#38959)

There is no need to check that the `ref.node` is of any particular type
because immediately after this check the entry is tested to see if it passes
`isClassDeclarationReference()`.

The only difference is that the error that is reported is slightly different
in the case that it is a `ref` but not one of the TS node types.

Previously:

```
`Value at position ${idx} in the NgModule.${arrayName} of ${
                className} is not a reference`
```

now

```
`Value at position ${idx} in the NgModule.${arrayName} of ${
                  className} is not a class`
```

Arguably the previous message was wrong, since this entry IS a reference
but is not a class.

PR Close #38959

packages/compiler-cli/src/ngtsc/annotations/src/ng_module.ts

@@ -540,8 +540,7 @@ export class NgModuleDecoratorHandler implements
   }
 
   // Verify that a `ts.Declaration` reference is a `ClassDeclaration` reference.
-  private isClassDeclarationReference(ref: Reference<ts.Declaration>):
-      ref is Reference<ClassDeclaration> {
+  private isClassDeclarationReference(ref: Reference): ref is Reference<ClassDeclaration> {
     return this.reflector.isClass(ref.node);
   }
 
@@ -568,7 +567,7 @@ export class NgModuleDecoratorHandler implements
       if (Array.isArray(entry)) {
         // Recurse into nested arrays.
         refList.push(...this.resolveTypeList(expr, entry, className, arrayName));
-      } else if (isDeclarationReference(entry)) {
+      } else if (entry instanceof Reference) {
         if (!this.isClassDeclarationReference(entry)) {
           throw createValueHasWrongTypeError(
               entry.node, entry,
@@ -593,9 +592,3 @@ function isNgModule(node: ClassDeclaration, compilation: ScopeData): boolean {
   return !compilation.directives.some(directive => directive.ref.node === node) &&
       !compilation.pipes.some(pipe => pipe.ref.node === node);
 }
-
-function isDeclarationReference(ref: any): ref is Reference<ts.Declaration> {
-  return ref instanceof Reference &&
-      (ts.isClassDeclaration(ref.node) || ts.isFunctionDeclaration(ref.node) ||
-       ts.isVariableDeclaration(ref.node));
-}