LibWeb: Allow focusable for the first summary child of a detail element

Author: https://github.com/lpas
Commit: bd56fdc57b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6780
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/HTML/HTMLSummaryElement.cpp

@@ -41,7 +41,7 @@ void HTMLSummaryElement::activation_behavior(DOM::Event const&)
 }
 
 // https://html.spec.whatwg.org/multipage/interactive-elements.html#summary-for-its-parent-details
-bool HTMLSummaryElement::is_summary_for_its_parent_details()
+bool HTMLSummaryElement::is_summary_for_its_parent_details() const
 {
     // A summary element is a summary for its parent details if the following algorithm returns true:
 
@@ -64,6 +64,13 @@ bool HTMLSummaryElement::is_summary_for_its_parent_details()
     return true;
 }
 
+// https://html.spec.whatwg.org/multipage/interaction.html#the-tabindex-attribute:the-summary-element
+bool HTMLSummaryElement::is_focusable() const
+{
+    // summary elements that are the first summary element child of a details element
+    return Base::is_focusable() || is_summary_for_its_parent_details();
+}
+
 HTMLSummaryElement::~HTMLSummaryElement() = default;
 
 void HTMLSummaryElement::initialize(JS::Realm& realm)

Libraries/LibWeb/HTML/HTMLSummaryElement.h

@@ -21,10 +21,11 @@ public:
     // https://www.w3.org/TR/html-aria/#el-details
     virtual Optional<ARIA::Role> default_role() const override { return ARIA::Role::button; }
 
-    bool is_summary_for_its_parent_details();
+    bool is_summary_for_its_parent_details() const;
 
     virtual bool has_activation_behavior() const override;
     virtual void activation_behavior(DOM::Event const&) override;
+    virtual bool is_focusable() const override;
 
 private:
     HTMLSummaryElement(DOM::Document&, DOM::QualifiedName);