LibWeb: Remove declarations for LineBoxFragment methods that don't exist

Userland/Libraries/LibWeb/Layout/LineBoxFragment.h

@@ -67,10 +67,6 @@ public:
 
     Gfx::FloatRect selection_rect(Gfx::Font const&) const;
 
-    float height_of_inline_level_box(LayoutState const&) const;
-    float top_of_inline_level_box(LayoutState const&) const;
-    float bottom_of_inline_level_box(LayoutState const&) const;
-
 private:
     Node const& m_layout_node;
     int m_start { 0 };