LibWeb: Add Contrast preference

Author: https://github.com/lukewarlow 🔰
Commit: ee64684565
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/146
Reviewed-by: https://github.com/AtkinsSJ

Userland/Libraries/LibWeb/CSS/PreferredContrast.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024, the Ladybird developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/CSS/PreferredContrast.h>
+
+namespace Web::CSS {
+
+PreferredContrast preferred_contrast_from_string(StringView value)
+{
+    if (value.equals_ignoring_ascii_case("less"sv))
+        return PreferredContrast::Less;
+    if (value.equals_ignoring_ascii_case("more"sv))
+        return PreferredContrast::More;
+    if (value.equals_ignoring_ascii_case("no-preference"sv))
+        return PreferredContrast::NoPreference;
+    return PreferredContrast::Auto;
+}
+
+StringView preferred_contrast_to_string(PreferredContrast value)
+{
+    switch (value) {
+    case PreferredContrast::Auto:
+        return "auto"sv;
+    case PreferredContrast::Less:
+        return "less"sv;
+    case PreferredContrast::More:
+        return "more"sv;
+    case PreferredContrast::NoPreference:
+        return "no-preference"sv;
+    }
+    VERIFY_NOT_REACHED();
+}
+
+}