fix(ivy): ensure @nocollapse is added to static fields (#28050)

ngtsc has a hack to add @nocollapse jsdoc annotations to generated static
fields. This hack is currently broken (likely due to a TypeScript change
in the way writeFile() works).

This commit fixes the hack and introduces an ngtsc_spec test to ensure it
does not regress again.

PR Close #28050

packages/compiler-cli/src/ngtsc/program.ts

@@ -227,7 +227,7 @@ export class NgtscProgram implements api.Program {
           if (fileName.endsWith('.d.ts')) {
             data = sourceFiles.reduce(
                 (data, sf) => this.compilation !.transformedDtsFor(sf.fileName, data), data);
-          } else if (this.closureCompilerEnabled && fileName.endsWith('.ts')) {
+          } else if (this.closureCompilerEnabled && fileName.endsWith('.js')) {
             data = nocollapseHack(data);
           }
           this.host.writeFile(fileName, data, writeByteOrderMark, onError, sourceFiles);

packages/compiler-cli/test/ngtsc/ngtsc_spec.ts

@@ -109,6 +109,27 @@ describe('ngtsc behavioral tests', () => {
     expect(jsContents).toContain('Hello World');
   });
 
+  it('should add @nocollapse to static fields when closure annotations are requested', () => {
+    env.tsconfig({
+      'annotateForClosureCompiler': true,
+    });
+    env.write('test.ts', `
+        import {Component} from '@angular/core';
+
+        @Component({
+          selector: 'test-cmp',
+          templateUrl: './dir/test.html',
+        })
+        export class TestCmp {}
+    `);
+    env.write('dir/test.html', '<p>Hello World</p>');
+
+    env.driveMain();
+
+    const jsContents = env.getContents('test.js');
+    expect(jsContents).toContain('/** @nocollapse */ TestCmp.ngComponentDef');
+  });
+
   it('should compile Components with a templateUrl in a different rootDir', () => {
     env.tsconfig({}, ['./extraRootDir']);
     env.write('extraRootDir/test.html', '<p>Hello World</p>');