LibWeb: Move border width and color into LayoutStyle

To make this possible, I also had to give each LayoutNode a Document&
so it can resolve document-specific colors correctly. There's probably
ways to avoid having this extra member by resolving colors later, but
this works for now.

Libraries/LibWeb/Layout/LayoutReplaced.cpp

@@ -30,8 +30,8 @@
 
 namespace Web {
 
-LayoutReplaced::LayoutReplaced(const Element& element, NonnullRefPtr<StyleProperties> style)
-    : LayoutBox(&element, move(style))
+LayoutReplaced::LayoutReplaced(Document& document, const Element& element, NonnullRefPtr<StyleProperties> style)
+    : LayoutBox(document, &element, move(style))
 {
     // FIXME: Allow non-inline replaced elements.
     set_inline(true);