LibWeb: Validate form submissions whose submitter is not form-associated

The spec for checking the no-validate state ends with a default return
value of "false". However, we were only hitting this case for form-
associated elements. If the submitter is the form itself, we want to
enter the form validation steps.

Libraries/LibWeb/HTML/HTMLFormElement.cpp

@@ -96,6 +96,16 @@ WebIDL::ExceptionOr<void> HTMLFormElement::implicitly_submit_form()
     return {};
 }
 
+// https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#concept-fs-novalidate
+static bool novalidate_state(HTMLElement const& element)
+{
+    // The no-validate state of an element is true if the element is a submit button and the element's formnovalidate
+    // attribute is present, or if the element's form owner's novalidate attribute is present, and false otherwise.
+    if (auto const* form_associated_element = as_if<FormAssociatedElement>(element))
+        return form_associated_element->novalidate_state();
+    return false;
+}
+
 // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#concept-form-submit
 WebIDL::ExceptionOr<void> HTMLFormElement::submit_form(GC::Ref<HTMLElement> submitter, SubmitFormOptions options)
 {
@@ -142,8 +152,7 @@ WebIDL::ExceptionOr<void> HTMLFormElement::submit_form(GC::Ref<HTMLElement> subm
         // 4. If the submitter element's no-validate state is false, then interactively validate the constraints
         //    of form and examine the result. If the result is negative (i.e., the constraint validation concluded
         //    that there were invalid fields and probably informed the user of this), then:
-        auto* form_associated_element = as_if<FormAssociatedElement>(*submitter);
-        if (form_associated_element && !form_associated_element->novalidate_state()) {
+        if (!novalidate_state(submitter)) {
             auto validation_result = interactively_validate_constraints();
             if (!validation_result) {
                 // 1. Set form's firing submission events to false.

Tests/LibWeb/Text/expected/wpt-import/html/semantics/forms/the-select-element/select-validity.tentative.txt

@@ -2,6 +2,7 @@ Harness status: OK
 
 Found 2 tests
 
-2 Fail
+1 Pass
+1 Fail
 Fail	Validation for placeholder option
-Fail	Check form not submitted for invalid select
+Pass	Check form not submitted for invalid select