LibWeb: Bring Document closer to spec

Userland/Libraries/LibWeb/DOM/Document.h

@@ -67,6 +67,9 @@ public:
     void set_url(const AK::URL& url) { m_url = url; }
     AK::URL url() const { return m_url; }
 
+    String url_string() const { return m_url.to_string(); }
+    String document_uri() const { return m_url.to_string(); }
+
     Origin origin() const;
     void set_origin(Origin const& origin);
 

Userland/Libraries/LibWeb/DOM/Document.idl

@@ -29,6 +29,9 @@ interface Document : Node {
 
     readonly attribute DOMImplementation implementation;
 
+    [ImplementedAs=url_string] readonly attribute USVString URL;
+    readonly attribute USVString documentURI;
+
     readonly attribute DOMString characterSet;
     readonly attribute DOMString charset;
     readonly attribute DOMString inputEncoding;