test: replace (webContents as any).destroy() with webContents.destroy() (#36653)

Co-authored-by: Milan Burda <miburda@microsoft.com>
Co-authored-by: John Kleinschmidt <jkleinsc@electronjs.org>

spec/node-spec.ts

@@ -790,7 +790,7 @@ describe('node feature', () => {
               }
             })`))
             .then(() => {
-              (w as any).destroy();
+              w.destroy();
               child.send('plz-quit');
               done();
             });