LibWeb: Return empty string if object element data URL is invalid

Author: https://github.com/tcl3
Commit: c61262684b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1080

Tests/LibWeb/Text/input/HTML/invalid-url-attribute-values.html

@@ -4,6 +4,7 @@
     test(() => {
         const elementList = [
             { "img": "currentSrc" },
+            { "object": "data" },
         ];
         for (const elementDescriptor of elementList) {
             [elementName, propertyName] = Object.entries(elementDescriptor)[0];