fix order of arguments validation in Array.prototype.flat polyfill

Author: zloirock

CHANGELOG.md

@@ -12,6 +12,7 @@
 - Fixed double `.return()` calling in case of throwing error in this method in the internal `iterate` helper that affected some polyfills
 - Fixed closing iterator on `IteratorValue` errors in the internal `iterate` helper that affected some polyfills
 - Fixed iterator closing in `Array.from` polyfill on failure to create array property
+- Fixed order of arguments validation in `Array.prototype.flat` polyfill
 - Fixed handling strings as iterables in `Iterator.{ zip, zipKeyed }` polyfills
 - Fixed some cases of iterators closing in `Iterator.{ zip, zipKeyed }` polyfills
 - Fixed a lack of early error in `Iterator.concat` polyfill on primitive as an iterator

packages/core-js/modules/es.array.flat.js

@@ -13,8 +13,9 @@ $({ target: 'Array', proto: true }, {
     var depthArg = arguments.length ? arguments[0] : undefined;
     var O = toObject(this);
     var sourceLen = lengthOfArrayLike(O);
+    var depthNum = depthArg === undefined ? 1 : toIntegerOrInfinity(depthArg);
     var A = arraySpeciesCreate(O, 0);
-    flattenIntoArray(A, O, O, sourceLen, 0, depthArg === undefined ? 1 : toIntegerOrInfinity(depthArg));
+    flattenIntoArray(A, O, O, sourceLen, 0, depthNum);
     return A;
   }
 });