LibWeb: Change paint_all_borders() to accept only device pixel values

By consistently accepting only device pixel values instead of a mix of
CSSPixels and DevicePixels values, we can simplify the implementation
of paint_border() and paint_all_borders().

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -482,6 +482,7 @@ set(SOURCES
     Painting/BorderRadiiData.cpp
     Painting/BorderPainting.cpp
     Painting/BorderRadiusCornerClipper.cpp
+    Painting/BordersData.cpp
     Painting/ButtonPaintable.cpp
     Painting/CanvasPaintable.cpp
     Painting/CheckBoxPaintable.cpp