fix(#309): Use flatMap if supported by runtime

Author: pete-murphy

src/Control/Bind.js

@@ -1,4 +1,10 @@
 export const arrayBind = function (arr) {
+  if (typeof Array.prototype.flatMap === "function") {
+    return function (f) {
+      return arr.flatMap(f);
+    };
+  }
+
   return function (f) {
     var result = [];
     for (var i = 0, l = arr.length; i < l; i++) {