Ladybird/Qt: Resize the viewport when window resize is requested

Previously, when a window resize was programatically requested
through WebDriver, we would update the size of the entire window. We
now ensure that the portion of the window containing the WebView is
set to the size requested.

This fixes some WPT tests where a specific viewport size is required.

Ladybird/Qt/BrowserWindow.cpp

@@ -1151,6 +1151,7 @@ void BrowserWindow::resizeEvent(QResizeEvent* event)
     QWidget::resizeEvent(event);
 
     for_each_tab([&](auto& tab) {
+        tab.view().set_viewport_size({ static_cast<int>(tab.view().width() * m_device_pixel_ratio), static_cast<int>(tab.view().height() * m_device_pixel_ratio) });
         tab.view().set_window_size({ frameSize().width() * m_device_pixel_ratio, frameSize().height() * m_device_pixel_ratio });
     });
 }

Ladybird/Qt/Tab.cpp

@@ -390,8 +390,9 @@ Tab::Tab(BrowserWindow* window, WebContentOptions const& web_content_options, St
     };
 
     view().on_resize_window = [this](auto const& size) {
-        m_window->resize(size.width(), size.height());
-        return Gfx::IntSize { m_window->width(), m_window->height() };
+        auto new_window_size = m_window->size() - m_view->size() + QSize { size.width(), size.height() };
+        m_window->resize(new_window_size);
+        return Gfx::IntSize { m_view->width(), m_view->height() };
     };
 
     view().on_maximize_window = [this]() {