querySelector cache always misses

The caching logic added to `querySelector` by https://github.com/capricorn86/happy-dom/pull/1359 is incomplete: It [reads `cachedResult?.result`](https://github.com/capricorn86/happy-dom/blob/master/packages/happy-dom/src/query-selector/QuerySelector.ts#L111-L116) but never writes to it.