LibWeb: Handle undefined arguments correctly in the Option constructor

The hand-rolled factory function wasn't handling undefined values
entirely correctly.

Libraries/LibWeb/Bindings/OptionConstructor.cpp

@@ -45,6 +45,11 @@ JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> OptionConstructor::construct
     auto& vm = this->vm();
     auto& realm = *vm.current_realm();
 
+    // NOTE: This implements the default value for the `text` parameter (the empty string "").
+    auto text_value = vm.argument(0);
+    if (text_value.is_undefined())
+        text_value = &vm.empty_string();
+
     // 1. Let document be the current principal global object's associated Document.
     auto& window = verify_cast<HTML::Window>(HTML::current_principal_global_object());
     auto& document = window.associated_document();
@@ -54,16 +59,14 @@ JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> OptionConstructor::construct
     JS::NonnullGCPtr<HTML::HTMLOptionElement> option_element = verify_cast<HTML::HTMLOptionElement>(*element);
 
     // 3. If text is not the empty string, then append to option a new Text node whose data is text.
-    if (vm.argument_count() > 0) {
-        auto text = TRY(vm.argument(0).to_string(vm));
-        if (!text.is_empty()) {
-            auto new_text_node = realm.create<DOM::Text>(document, text);
-            MUST(option_element->append_child(*new_text_node));
-        }
+    auto text = TRY(text_value.to_string(vm));
+    if (!text.is_empty()) {
+        auto new_text_node = realm.create<DOM::Text>(document, text);
+        MUST(option_element->append_child(*new_text_node));
     }
 
     // 4. If value is given, then set an attribute value for option using "value" and value.
-    if (vm.argument_count() > 1) {
+    if (!vm.argument(1).is_undefined()) {
         auto value = TRY(vm.argument(1).to_string(vm));
         MUST(option_element->set_attribute(HTML::AttributeNames::value, value));
     }

Tests/LibWeb/Text/expected/wpt-import/html/semantics/forms/the-option-element/option-element-constructor.txt

@@ -6,15 +6,14 @@ Rerun
 
 Found 11 tests
 
-10 Pass
-1 Fail
+11 Pass
 Details
 Result	Test Name	MessagePass	Option constructor with no arguments	
 Pass	Option constructor with falsy arguments	
 Pass	Option constructor creates HTMLOptionElement with specified text and value	
 Pass	Option constructor handles selectedness correctly when specified with defaultSelected only	
 Pass	Option constructor handles selectedness correctly, even when incongruous with defaultSelected	
-Fail	Option constructor treats undefined text and value correctly	
+Pass	Option constructor treats undefined text and value correctly	
 Pass	Option constructor treats empty text and value correctly	
 Pass	Option constructor treats falsy selected and defaultSelected correctly	
 Pass	Option constructor treats truthy selected and defaultSelected correctly