LibWeb: Add Fullscreen API event handlers to IDL

This commit adds the event handlers for fullscreen API to Document and
Element.

This also adds an extremely light-weight (and stupid) policy check
which is required by the fullscreen api. However, policy permission
checks are not implemented yet.

Libraries/LibWeb/DOM/Document.cpp

@@ -4387,6 +4387,9 @@ bool Document::is_allowed_to_use_feature(PolicyControlledFeature feature) const
     case PolicyControlledFeature::FocusWithoutUserActivation:
         // FIXME: Implement allowlist for this.
         return true;
+    case PolicyControlledFeature::Fullscreen:
+        // FIXME: Implement the permissions policy specification
+        return true;
     }
 
     // 4. Return false.
@@ -6246,6 +6249,26 @@ void Document::append_pending_fullscreen_change(PendingFullscreenEvent::Type typ
     m_pending_fullscreen_events.append(PendingFullscreenEvent { type, element });
 }
 
+WebIDL::CallbackType* Document::onfullscreenchange()
+{
+    return event_handler_attribute(HTML::EventNames::fullscreenchange);
+}
+
+void Document::set_onfullscreenchange(WebIDL::CallbackType* value)
+{
+    set_event_handler_attribute(HTML::EventNames::fullscreenchange, value);
+}
+
+WebIDL::CallbackType* Document::onfullscreenerror()
+{
+    return event_handler_attribute(HTML::EventNames::fullscreenerror);
+}
+
+void Document::set_onfullscreenerror(WebIDL::CallbackType* value)
+{
+    set_event_handler_attribute(HTML::EventNames::fullscreenerror, value);
+}
+
 // https://dom.spec.whatwg.org/#document-allow-declarative-shadow-roots
 void Document::set_allow_declarative_shadow_roots(bool allow)
 {

Libraries/LibWeb/DOM/Document.h

@@ -154,6 +154,7 @@ struct ElementCreationOptions {
 enum class PolicyControlledFeature : u8 {
     Autoplay,
     FocusWithoutUserActivation,
+    Fullscreen,
 };
 
 struct PendingFullscreenEvent {
@@ -908,6 +909,12 @@ public:
     void run_fullscreen_steps();
     void append_pending_fullscreen_change(PendingFullscreenEvent::Type type, GC::Ref<Element> element);
 
+    // https://fullscreen.spec.whatwg.org/#api
+    [[nodiscard]] WebIDL::CallbackType* onfullscreenchange();
+    void set_onfullscreenchange(WebIDL::CallbackType*);
+    [[nodiscard]] WebIDL::CallbackType* onfullscreenerror();
+    void set_onfullscreenerror(WebIDL::CallbackType*);
+
 protected:
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;

Libraries/LibWeb/DOM/Document.idl

@@ -156,6 +156,10 @@ interface Document : Node {
     // special event handler IDL attributes that only apply to Document objects
     [LegacyLenientThis] attribute EventHandler onreadystatechange;
     attribute EventHandler onvisibilitychange;
+
+    // https://fullscreen.spec.whatwg.org/#api
+    attribute EventHandler onfullscreenchange;
+    attribute EventHandler onfullscreenerror;
 };
 
 dictionary ElementCreationOptions {

Libraries/LibWeb/DOM/Element.cpp

@@ -1905,6 +1905,26 @@ WebIDL::ExceptionOr<void> Element::insert_adjacent_html(String const& position,
     return {};
 }
 
+GC::Ptr<WebIDL::CallbackType> Element::onfullscreenchange()
+{
+    return event_handler_attribute(HTML::EventNames::fullscreenchange);
+}
+
+void Element::set_onfullscreenchange(GC::Ptr<WebIDL::CallbackType> event_handler)
+{
+    set_event_handler_attribute(HTML::EventNames::fullscreenchange, event_handler);
+}
+
+GC::Ptr<WebIDL::CallbackType> Element::onfullscreenerror()
+{
+    return event_handler_attribute(HTML::EventNames::fullscreenerror);
+}
+
+void Element::set_onfullscreenerror(GC::Ptr<WebIDL::CallbackType> event_handler)
+{
+    set_event_handler_attribute(HTML::EventNames::fullscreenerror, event_handler);
+}
+
 // https://dom.spec.whatwg.org/#insert-adjacent
 WebIDL::ExceptionOr<GC::Ptr<Node>> Element::insert_adjacent(StringView where, GC::Ref<Node> node)
 {

Libraries/LibWeb/DOM/Element.h

@@ -232,6 +232,12 @@ public:
 
     WebIDL::ExceptionOr<void> insert_adjacent_html(String const& position, String const&);
 
+    GC::Ptr<WebIDL::CallbackType> onfullscreenchange();
+    void set_onfullscreenchange(GC::Ptr<WebIDL::CallbackType>);
+
+    GC::Ptr<WebIDL::CallbackType> onfullscreenerror();
+    void set_onfullscreenerror(GC::Ptr<WebIDL::CallbackType>);
+
     WebIDL::ExceptionOr<String> outer_html() const;
     WebIDL::ExceptionOr<void> set_outer_html(String const&);
 

Libraries/LibWeb/DOM/Element.idl

@@ -33,6 +33,17 @@ dictionary CheckVisibilityOptions {
     boolean visibilityProperty = false;
 };
 
+// https://fullscreen.spec.whatwg.org/#api
+enum FullscreenNavigationUI {
+    "auto",
+    "show",
+    "hide"
+};
+
+dictionary FullscreenOptions {
+    FullscreenNavigationUI navigationUI = "auto";
+};
+
 // https://dom.spec.whatwg.org/#element
 [Exposed=Window]
 interface Element : Node {
@@ -124,6 +135,10 @@ interface Element : Node {
     undefined setPointerCapture(long pointerId);
     undefined releasePointerCapture(long pointerId);
     boolean hasPointerCapture(long pointerId);
+
+    // partial interface for https://fullscreen.spec.whatwg.org/#api
+    attribute EventHandler onfullscreenchange;
+    attribute EventHandler onfullscreenerror;
 };
 
 dictionary GetHTMLOptions {