LibWeb: Stub out missing cross origin properties on the window object

Previously, trying to access the `close`, `closed` or `blur` properties
on a cross origin window would cause a crash.

Userland/Libraries/LibWeb/HTML/Window.cpp

@@ -874,6 +874,21 @@ String Window::status() const
     return m_status;
 }
 
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-window-close
+void Window::close()
+{
+    // FIXME: Implement this properly
+    dbgln("(STUBBED) Window::close()");
+}
+
+// https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-window-closed
+bool Window::closed() const
+{
+    // FIXME: Implement this properly
+    dbgln("(STUBBED) Window::closed");
+    return false;
+}
+
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-window-status
 void Window::set_status(String const& status)
 {
@@ -918,6 +933,12 @@ void Window::focus()
     //           indicate to the user that the page is attempting to gain focus.
 }
 
+// https://html.spec.whatwg.org/multipage/interaction.html#dom-window-blur
+void Window::blur()
+{
+    // The blur() method steps are to do nothing.
+}
+
 // https://html.spec.whatwg.org/multipage/window-object.html#dom-frames
 JS::NonnullGCPtr<WindowProxy> Window::frames() const
 {

Userland/Libraries/LibWeb/HTML/Window.h

@@ -135,11 +135,14 @@ public:
     String name() const;
     void set_name(String const&);
     String status() const;
+    void close();
+    bool closed() const;
     void set_status(String const&);
     [[nodiscard]] JS::NonnullGCPtr<Location> location();
     JS::NonnullGCPtr<History> history() const;
     JS::NonnullGCPtr<Navigation> navigation();
     void focus();
+    void blur();
 
     JS::NonnullGCPtr<WindowProxy> frames() const;
     u32 length();

Userland/Libraries/LibWeb/HTML/Window.idl

@@ -24,11 +24,14 @@ interface Window : EventTarget {
     [LegacyUnforgeable] readonly attribute Document document;
     attribute DOMString name;
     attribute DOMString status;
+    undefined close();
+    readonly attribute boolean closed;
     [PutForwards=href, LegacyUnforgeable] readonly attribute Location location;
     readonly attribute History history;
     readonly attribute Navigation navigation;
     readonly attribute CustomElementRegistry customElements;
     undefined focus();
+    undefined blur();
 
     // other browsing contexts
     [Replaceable] readonly attribute WindowProxy frames;