LibWeb: Add definitions from '2.1. URL' in the Fetch spec

Userland/Libraries/LibWeb/Fetch/Infrastructure/URL.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Array.h>
+#include <AK/URL.h>
+
+namespace Web::Fetch {
+
+// https://fetch.spec.whatwg.org/#local-scheme
+// A local scheme is "about", "blob", or "data".
+inline constexpr Array LOCAL_SCHEMES = {
+    "about"sv, "blob"sv, "data"sv
+};
+
+// https://fetch.spec.whatwg.org/#http-scheme
+// An HTTP(S) scheme is "http" or "https".
+inline constexpr Array HTTP_SCHEMES = {
+    "http"sv, "https"sv
+};
+
+// https://fetch.spec.whatwg.org/#fetch-scheme
+// A fetch scheme is "about", "blob", "data", "file", or an HTTP(S) scheme.
+inline constexpr Array FETCH_SCHEMES = {
+    "about"sv, "blob"sv, "data"sv, "file"sv, "http"sv, "https"sv
+};
+
+[[nodiscard]] bool is_local_url(AK::URL const&);
+
+}