guard, info on never null, more general array rt

std/portable/index.js

@@ -229,7 +229,13 @@ globalScope["isArrayLike"] = function isArrayLike(expr) {
     && typeof expr.length === 'number'
     && expr.length >= 0
     && Math.trunc(expr.length) === expr.length;
-}
+};
+
+Array.create = function(capacity) {
+  var arr = new Array(capacity);
+  arr.length = 0;
+  return arr;
+};
 
 globalScope["isDefined"] = function isDefined(expr) {
   return typeof expr !== "undefined";