LibWeb/CSS: Add "text" into list of possible "background-box" values

Author: https://github.com/zacbrannelly 🔰
Commit: 4a3680cafc
Pull-request: https://github.com/SerenityOS/serenity/pull/23373
Reviewed-by: https://github.com/kalenikaliaksandr ✅

Userland/Libraries/LibWeb/Layout/Node.cpp

@@ -392,6 +392,8 @@ void NodeWithStyle::apply_style(const CSS::StyleProperties& computed_style)
                     return CSS::BackgroundBox::ContentBox;
                 case CSS::ValueID::PaddingBox:
                     return CSS::BackgroundBox::PaddingBox;
+                case CSS::ValueID::Text:
+                    return CSS::BackgroundBox::Text;
                 default:
                     VERIFY_NOT_REACHED();
                 }