Refactoring for immutable nodes

Src/AST/Myc.Ast.Script.pas

@@ -511,7 +511,7 @@ begin
                 raise Exception.Create('Syntax Error: Missing value for key ' + fieldName + ' in record literal.');
             fieldValue := ParseExpression.Node;
 
-            fields.Add(TRecordFieldLiteral.Create(TKeywordNode.Create(TKeywordRegistry.Intern(fieldName)), fieldValue));
+            fields.Add(TRecordFieldLiteral.Create(TAst.Keyword(fieldName), fieldValue));
         end;
 
         Result := TAst.RecordLiteral(fields.ToArray);
@@ -945,7 +945,7 @@ var
     arg: IAstNode;
 begin
     // Special case for (quote ...) to print it as '...
-    if (Node.Callee is TIdentifierNode) and (TIdentifierNode(Node.Callee).Name = 'quote') and (Length(Node.Arguments) = 1) then
+    if (Node.Callee.Kind = akIdentifier) and (Node.Callee.AsIdentifier.Name = 'quote') and (Length(Node.Arguments) = 1) then
     begin
         Append('''');
         Node.Arguments[0].Accept(Self);