fixup! Bug 40475: Include clearing CORS preflight cache
added a nullptr check before accessing sPreflightCache. sPreflightCache is created on demand via a call to EnsurePreflightCache() within nsCORSPreflightListener::AddResultToCache(). So, if no result has been cached, the object is never created and attempting to clear it will segfault
Fixes #40476 (closed)
Edited by morgan