Remove outdated comment (#4190)

We now always return a conditional group.

src/language-js/printer-estree.js

@@ -3181,9 +3181,6 @@ function printArgumentsList(path, options, print) {
     return concat(parts);
   }, "arguments");
 
-  // This is just an optimization; I think we could return the
-  // conditional group for all function calls, but it's more expensive
-  // so only do it for specific forms.
   const shouldGroupFirst = shouldGroupFirstArg(args);
   const shouldGroupLast = shouldGroupLastArg(args);
   if (shouldGroupFirst || shouldGroupLast) {