LibWeb/HTML: Update HTMLButtonElement.type to match spec changes

Corresponds to part of https://github.com/whatwg/html/pull/9841 and then
https://github.com/whatwg/html/pull/11047

Adding `Auto` as a type state feels a little odd, as it's not an actual
type allowed in HTML. However, it's the default state when the value is
missing or invalid, which works out the same, as long as we never
serialize "auto", which we don't.

Libraries/LibWeb/HTML/HTMLButtonElement.cpp

@@ -37,12 +37,44 @@ HTMLButtonElement::TypeAttributeState HTMLButtonElement::type_state() const
     ENUMERATE_HTML_BUTTON_TYPE_ATTRIBUTES
 #undef __ENUMERATE_HTML_BUTTON_TYPE_ATTRIBUTE
 
-    // The missing value default and invalid value default are the Submit Button state.
-    return HTMLButtonElement::TypeAttributeState::Submit;
+    // The attribute's missing value default and invalid value default are both the Auto state.
+    // https://html.spec.whatwg.org/multipage/form-elements.html#attr-button-type-auto-state
+    return HTMLButtonElement::TypeAttributeState::Auto;
 }
 
-WebIDL::ExceptionOr<void> HTMLButtonElement::set_type(String const& type)
+// https://html.spec.whatwg.org/multipage/form-elements.html#dom-button-type
+String HTMLButtonElement::type_for_bindings() const
 {
+    // The type getter steps are:
+    // 1. If this is a submit button, then return "submit".
+    if (is_submit_button())
+        return "submit"_string;
+
+    // 2. Let state be this's type attribute.
+    auto state = type_state();
+
+    // 3. Assert: state is not in the Submit Button state.
+    VERIFY(state != TypeAttributeState::Submit);
+
+    // 4. If state is in the Auto state, then return "button".
+    if (state == TypeAttributeState::Auto)
+        return "button"_string;
+
+    // 5. Return the keyword value corresponding to state.
+    switch (state) {
+#define __ENUMERATE_HTML_BUTTON_TYPE_ATTRIBUTE(keyword, state) \
+    case TypeAttributeState::state:                            \
+        return #keyword##_string;
+        ENUMERATE_HTML_BUTTON_TYPE_ATTRIBUTES
+#undef __ENUMERATE_HTML_BUTTON_TYPE_ATTRIBUTE
+    }
+    VERIFY_NOT_REACHED();
+}
+
+// https://html.spec.whatwg.org/multipage/form-elements.html#dom-button-type
+WebIDL::ExceptionOr<void> HTMLButtonElement::set_type_for_bindings(String const& type)
+{
+    // The type setter steps are to set the type content attribute to the given value.
     return set_attribute(HTML::AttributeNames::type, type);
 }
 
@@ -68,8 +100,17 @@ i32 HTMLButtonElement::default_tab_index_value() const
 // https://html.spec.whatwg.org/multipage/form-elements.html#the-button-element:concept-submit-button
 bool HTMLButtonElement::is_submit_button() const
 {
-    // A button element is said to be a submit button if the type attribute is in the Submit Button state.
-    return type_state() == TypeAttributeState::Submit;
+    // A button element is said to be a submit button if any of the following are true:
+    switch (type_state()) {
+        // - the type attribute is in the Auto state and both the command and commandfor content attributes are not present; or
+    case TypeAttributeState::Auto:
+        return !has_attribute(AttributeNames::command) && !has_attribute(AttributeNames::commandfor);
+        // - the type attribute is in the Submit Button state.
+    case TypeAttributeState::Submit:
+        return true;
+    default:
+        return false;
+    }
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#the-button-element:concept-fe-value
@@ -106,7 +147,11 @@ void HTMLButtonElement::activation_behavior(DOM::Event const& event)
         }
     }
 
-    // 4. Run the popover target attribute activation behavior given element and event's target.
+    // FIXME: 4. Let target be the result of running element's get the commandfor associated element.
+    // FIXME: 5. If target is not null:
+    //           ...
+
+    // 6. Otherwise, run the popover target attribute activation behavior given element and event's target.
     if (event.target() && event.target()->is_dom_node())
         PopoverInvokerElement::popover_target_activation_behaviour(*this, as<DOM::Node>(*event.target()));
 }