LibWeb: Remove unused VideoBox preferred width/height methods

These were copied from some other paintable, but were never used for
video.

Userland/Libraries/LibWeb/Layout/VideoBox.cpp

@@ -35,16 +35,6 @@ HTML::HTMLVideoElement const& VideoBox::dom_node() const
     return static_cast<HTML::HTMLVideoElement const&>(ReplacedBox::dom_node());
 }
 
-int VideoBox::preferred_width() const
-{
-    return dom_node().attribute(HTML::AttributeNames::width).to_int().value_or(dom_node().video_width());
-}
-
-int VideoBox::preferred_height() const
-{
-    return dom_node().attribute(HTML::AttributeNames::height).to_int().value_or(dom_node().video_height());
-}
-
 void VideoBox::prepare_for_replaced_layout()
 {
     auto width = static_cast<float>(dom_node().video_width());

Userland/Libraries/LibWeb/Layout/VideoBox.h

@@ -33,9 +33,6 @@ private:
 
     // ^JS::Cell
     virtual void finalize() override;
-
-    int preferred_width() const;
-    int preferred_height() const;
 };
 
 }