LibWeb: Remove unused code

The code that used these helpers has been moved a while ago to PageHost.

Userland/Libraries/LibWeb/Page/EventHandler.cpp

@@ -130,20 +130,6 @@ EventHandler::EventHandler(Badge<HTML::BrowsingContext>, HTML::BrowsingContext&
 
 EventHandler::~EventHandler() = default;
 
-Layout::Viewport const* EventHandler::layout_root() const
-{
-    if (!m_browsing_context->active_document())
-        return nullptr;
-    return m_browsing_context->active_document()->layout_node();
-}
-
-Layout::Viewport* EventHandler::layout_root()
-{
-    if (!m_browsing_context->active_document())
-        return nullptr;
-    return m_browsing_context->active_document()->layout_node();
-}
-
 Painting::PaintableBox* EventHandler::paint_root()
 {
     if (!m_browsing_context->active_document())

Userland/Libraries/LibWeb/Page/EventHandler.h

@@ -51,9 +51,6 @@ private:
     };
     Optional<Target> target_for_mouse_position(CSSPixelPoint position);
 
-    Layout::Viewport* layout_root();
-    Layout::Viewport const* layout_root() const;
-
     Painting::PaintableBox* paint_root();
     Painting::PaintableBox const* paint_root() const;