LibWeb: Port Element::set_attribute_value from ByteString

Also making set_attribute_ns take a String instead of a FlyString as
this is only used as an Attr value and no FlyString properties are used.

Userland/Libraries/LibWeb/DOM/Element.cpp

@@ -224,13 +224,13 @@ WebIDL::ExceptionOr<QualifiedName> validate_and_extract(JS::Realm& realm, Option
 }
 
 // https://dom.spec.whatwg.org/#dom-element-setattributens
-WebIDL::ExceptionOr<void> Element::set_attribute_ns(Optional<FlyString> const& namespace_, FlyString const& qualified_name, FlyString const& value)
+WebIDL::ExceptionOr<void> Element::set_attribute_ns(Optional<FlyString> const& namespace_, FlyString const& qualified_name, String const& value)
 {
     // 1. Let namespace, prefix, and localName be the result of passing namespace and qualifiedName to validate and extract.
     auto extracted_qualified_name = TRY(validate_and_extract(realm(), namespace_, qualified_name));
 
     // 2. Set an attribute value for this using localName, value, and also prefix and namespace.
-    set_attribute_value(extracted_qualified_name.local_name(), value.to_deprecated_fly_string(), extracted_qualified_name.prefix(), extracted_qualified_name.namespace_());
+    set_attribute_value(extracted_qualified_name.local_name(), value, extracted_qualified_name.prefix(), extracted_qualified_name.namespace_());
 
     return {};
 }
@@ -242,7 +242,7 @@ void Element::append_attribute(Attr& attribute)
 }
 
 // https://dom.spec.whatwg.org/#concept-element-attributes-set-value
-void Element::set_attribute_value(FlyString const& local_name, ByteString const& value, Optional<FlyString> const& prefix, Optional<FlyString> const& namespace_)
+void Element::set_attribute_value(FlyString const& local_name, String const& value, Optional<FlyString> const& prefix, Optional<FlyString> const& namespace_)
 {
     // 1. Let attribute be the result of getting an attribute given namespace, localName, and element.
     auto* attribute = m_attributes->get_attribute_ns(namespace_, local_name);
@@ -253,14 +253,14 @@ void Element::set_attribute_value(FlyString const& local_name, ByteString const&
     if (!attribute) {
         QualifiedName name { local_name, prefix, namespace_ };
 
-        auto new_attribute = Attr::create(document(), move(name), MUST(String::from_byte_string(value)));
+        auto new_attribute = Attr::create(document(), move(name), value);
         m_attributes->append_attribute(new_attribute);
 
         return;
     }
 
     // 3. Change attribute to value.
-    attribute->change_attribute(MUST(String::from_byte_string(value)));
+    attribute->change_attribute(value);
 }
 
 // https://dom.spec.whatwg.org/#dom-element-setattributenode

Userland/Libraries/LibWeb/DOM/Element.h

@@ -104,8 +104,8 @@ public:
 
     WebIDL::ExceptionOr<void> set_attribute(FlyString const& name, String const& value);
 
-    WebIDL::ExceptionOr<void> set_attribute_ns(Optional<FlyString> const& namespace_, FlyString const& qualified_name, FlyString const& value);
-    void set_attribute_value(FlyString const& local_name, ByteString const& value, Optional<FlyString> const& prefix = {}, Optional<FlyString> const& namespace_ = {});
+    WebIDL::ExceptionOr<void> set_attribute_ns(Optional<FlyString> const& namespace_, FlyString const& qualified_name, String const& value);
+    void set_attribute_value(FlyString const& local_name, String const& value, Optional<FlyString> const& prefix = {}, Optional<FlyString> const& namespace_ = {});
     WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node(Attr&);
     WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node_ns(Attr&);
 

Userland/Services/WebContent/ConnectionFromClient.cpp

@@ -659,7 +659,7 @@ void ConnectionFromClient::set_dom_node_tag(i32 node_id, String const& name)
     auto new_element = Web::DOM::create_element(element.document(), name, element.namespace_uri(), element.prefix(), element.is_value()).release_value_but_fixme_should_propagate_errors();
 
     element.for_each_attribute([&](auto const& attribute) {
-        new_element->set_attribute_value(attribute.local_name(), attribute.value().to_byte_string(), attribute.prefix(), attribute.namespace_uri());
+        new_element->set_attribute_value(attribute.local_name(), attribute.value(), attribute.prefix(), attribute.namespace_uri());
     });
 
     while (auto* child_node = element.first_child()) {