LibWeb: Use standardized encoding names, add encoding attribute to document

Author: https://github.com/Lubrsi
Commit: ed2689c00a
Pull-request: https://github.com/SerenityOS/serenity/pull/4070
Reviewed-by: https://github.com/awesomekling

Libraries/LibWeb/DOM/Document.h

@@ -199,6 +199,14 @@ public:
     const String& content_type() const { return m_content_type; }
     void set_content_type(const String& content_type) { m_content_type = content_type; }
 
+    const String& encoding() const { return m_encoding; }
+    void set_encoding(const String& encoding) { m_encoding = encoding; }
+
+    // NOTE: These are intended for the JS bindings
+    const String& character_set() const { return encoding(); }
+    const String& charset() const { return encoding(); }
+    const String& input_encoding() const { return encoding(); }
+
     const NonnullRefPtr<DOMImplementation> implementation() { return m_implementation; }
 
 private:
@@ -262,6 +270,7 @@ private:
 
     String m_ready_state { "loading" };
     String m_content_type { "application/xml" };
+    String m_encoding { "UTF-8" };
 
     NonnullRefPtr<DOMImplementation> m_implementation;
 };

Libraries/LibWeb/DOM/Document.idl

@@ -2,6 +2,9 @@ interface Document : Node {
 
     readonly attribute DOMImplementation implementation;
 
+    readonly attribute DOMString characterSet;
+    readonly attribute DOMString charset;
+    readonly attribute DOMString inputEncoding;
     readonly attribute DOMString contentType;
 
     Element? getElementById(DOMString id);