We should replace all direct uses of ResourceLoader with Fetch. This is because using ResourceLoader bypasses many features that Fetch handles:

• All security mechanisms (CORS-preflight, Mixed Content, Content Security Policy, bad ports, Sec-Fetch-* headers, Referrer Policy, etc.)
• Service Workers (not yet implemented)
• Caching
• Redirects
• Blob URLs
• Resource Timing (not yet implemented, required for #226)
• Referrers
• More that I can't think as of writing.

These are the usages I could find:

• HTMLLinkElement

  ladybird/Libraries/LibWeb/HTML/HTMLLinkElement.cpp

  Lines 77 to 91 in ac590fe

  	// FIXME: Follow spec for fetching and processing these attributes as well
  	if (m_relationship & Relationship::Preload) {
  	// FIXME: Respect the "as" attribute.
  	LoadRequest request;
  	request.set_url(document().parse_url(get_attribute_value(HTML::AttributeNames::href)));
  	set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));
  	} else if (m_relationship & Relationship::DNSPrefetch) {
  	ResourceLoader::the().prefetch_dns(document().parse_url(get_attribute_value(HTML::AttributeNames::href)));
  	} else if (m_relationship & Relationship::Preconnect) {
  	ResourceLoader::the().preconnect(document().parse_url(get_attribute_value(HTML::AttributeNames::href)));
  	} else if (m_relationship & Relationship::Icon) {
  	auto favicon_url = document().parse_url(href());
  	auto favicon_request = LoadRequest::create_for_url_on_page(favicon_url, &document().page());
  	set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, favicon_request));
  	}

• Font Loading in StyleComputer.cpp

  ladybird/Libraries/LibWeb/CSS/StyleComputer.cpp

  Lines 246 to 252 in ac590fe

  	// HACK: We're crudely computing the referer value and shoving it into the
  	// request until fetch infrastructure is used here.
  	auto referrer_url = ReferrerPolicy::strip_url_for_use_as_referrer(m_style_computer.document().url());
  	if (referrer_url.has_value() && !request.headers().contains("Referer"))
  	request.set_header("Referer", referrer_url->serialize());
  	set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));

• CSSImportRule

  ladybird/Libraries/LibWeb/CSS/CSSImportRule.cpp

  Lines 36 to 43 in ac590fe

  	dbgln_if(CSS_LOADER_DEBUG, "CSSImportRule: Loading import URL: {}", m_url);
  	auto request = LoadRequest::create_for_url_on_page(m_url, &document.page());
  	// NOTE: Mark this rule as delaying the document load event *before* calling set_resource()
  	// as it may trigger a synchronous resource_did_load() callback.
  	m_document_load_event_delayer.emplace(document);
  	set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));

• HTMLObjectElement

  ladybird/Libraries/LibWeb/HTML/HTMLObjectElement.cpp

  Lines 211 to 216 in ac590fe

  	// 4. Let request be a new request whose URL is the resulting URL record, client is the element's node document's relevant settings object, destination is "object", credentials mode is "include", mode is "navigate", and whose use-URL-credentials flag is set.
  	auto request = LoadRequest::create_for_url_on_page(url, &document().page());
  	// 5. Fetch request, with processResponseEndOfBody given response res set to finalize and report timing with res, the element's node document's relevant global object, and "object".
  	// Fetching the resource must delay the load event of the element's node document until the task that is queued by the networking task source once the resource has been fetched (defined next) has been run.
  	set_resource(ResourceLoader::the().load_resource(Resource::Type::Generic, request));

With these replaced, we could remove load_resource and potentially badge load and load_unbuffered to only be called from Fetch.