LibWeb: Move window.confirm() to using a PageClient callback

This allows us to move the GUI::MessageBox out of DOM::Window and up to
the widget layer.

Userland/Libraries/LibWeb/DOM/Window.cpp

@@ -25,7 +25,6 @@
  */
 
 #include <LibGUI/DisplayLink.h>
-#include <LibGUI/MessageBox.h>
 #include <LibJS/Runtime/Function.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/DOM/Event.h>
@@ -67,8 +66,9 @@ void Window::alert(const String& message)
 
 bool Window::confirm(const String& message)
 {
-    auto confirm_result = GUI::MessageBox::show(nullptr, message, "Confirm", GUI::MessageBox::Type::Warning, GUI::MessageBox::InputType::OKCancel);
-    return confirm_result == GUI::Dialog::ExecResult::ExecOK;
+    if (auto* page = m_document.page())
+        return page->client().page_did_request_confirm(message);
+    return false;
 }
 
 i32 Window::set_interval(JS::Function& callback, i32 interval)

Userland/Libraries/LibWeb/InProcessWebView.cpp

@@ -420,4 +420,10 @@ void InProcessWebView::page_did_request_alert(const String& message)
     GUI::MessageBox::show(window(), message, "Alert", GUI::MessageBox::Type::Information);
 }
 
+bool InProcessWebView::page_did_request_confirm(const String& message)
+{
+    auto confirm_result = GUI::MessageBox::show(window(), message, "Confirm", GUI::MessageBox::Type::Warning, GUI::MessageBox::InputType::OKCancel);
+    return confirm_result == GUI::Dialog::ExecResult::ExecOK;
+}
+
 }

Userland/Libraries/LibWeb/InProcessWebView.h

@@ -106,6 +106,7 @@ private:
     virtual void page_did_layout() override;
     virtual void page_did_request_scroll_into_view(const Gfx::IntRect&) override;
     virtual void page_did_request_alert(const String&) override;
+    virtual bool page_did_request_confirm(const String&) override;
 
     void layout_and_sync_size();
 

Userland/Libraries/LibWeb/Page/Page.h

@@ -105,6 +105,7 @@ public:
     virtual void page_did_layout() { }
     virtual void page_did_request_scroll_into_view(const Gfx::IntRect&) { }
     virtual void page_did_request_alert(const String&) { }
+    virtual bool page_did_request_confirm(const String&) { return false; }
 };
 
 }