properly handle attr and style

As part of 6d509c4, the native code that handles attr and style should
have been changed to handle non-Maybe values.

src/Native/D3/Selection.js

@@ -189,15 +189,15 @@ Elm.Native.D3.Selection.make = function(elm) {
 
   function elm_attr(name, valfn) {
     name = JS.fromString(name);
-    valfn = safeValfn(valfn, safeOptEvaluator);
+    valfn = safeValfn(valfn, safeEvaluator);
     return function(k, selection, i) {
       return k(selection.attr(name, safeIndexed(i, valfn)), i);
     };
   }
 
   function elm_style(name, valfn) {
     name = JS.fromString(name);
-    valfn = safeValfn(valfn, safeOptEvaluator);
+    valfn = safeValfn(valfn, safeEvaluator);
     return function(k, selection, i) {
       return k(selection.style(name, safeIndexed(i, valfn)), i);
     };