Fix invalid_override_different_default_values_positional warning w/ r…

…eact 7.0.0

The existing lack of a default was also bad behavior, since passing
`null` as children would break.

lib/src/over_react_redux/over_react_redux.dart

@@ -479,7 +479,7 @@ class ReactJsReactReduxComponentFactoryProxy extends ReactJsContextComponentFact
   }) : super(jsClass, isProvider: isProvider, isConsumer: isConsumer, shouldConvertDomProps: shouldConvertDomProps);
 
   @override
-  ReactElement build(Map props, [List childrenArgs]) {
+  ReactElement build(Map props, [List childrenArgs = const []]) {
     return super.build(_generateReduxJsProps(props), childrenArgs);
   }