LibWeb: Add form associated element categories

Author: https://github.com/Lubrsi
Commit: 432d496ed6
Pull-request: https://github.com/SerenityOS/serenity/pull/12837

Userland/Libraries/LibWeb/HTML/HTMLButtonElement.h

@@ -16,6 +16,20 @@ public:
 
     HTMLButtonElement(DOM::Document&, DOM::QualifiedName);
     virtual ~HTMLButtonElement() override;
+
+    // ^FormAssociatedElement
+    // https://html.spec.whatwg.org/multipage/forms.html#category-listed
+    virtual bool is_listed() const override { return true; }
+
+    // https://html.spec.whatwg.org/multipage/forms.html#category-submit
+    virtual bool is_submittable() const override { return true; }
+
+    // https://html.spec.whatwg.org/multipage/forms.html#category-autocapitalize
+    virtual bool is_auto_capitalize_inheriting() const override { return true; }
+
+    // ^HTMLElement
+    // https://html.spec.whatwg.org/multipage/forms.html#category-label
+    virtual bool is_labelable() const override { return true; }
 };
 
 }