update

node_modules/core-js/modules/es7.array.flatten.js

@@ -0,0 +1,21 @@
+'use strict';
+// https://tc39.github.io/proposal-flatMap/#sec-Array.prototype.flatten
+var $export = require('./_export');
+var flattenIntoArray = require('./_flatten-into-array');
+var toObject = require('./_to-object');
+var toLength = require('./_to-length');
+var toInteger = require('./_to-integer');
+var arraySpeciesCreate = require('./_array-species-create');
+
+$export($export.P, 'Array', {
+  flatten: function flatten(/* depthArg = 1 */) {
+    var depthArg = arguments[0];
+    var O = toObject(this);
+    var sourceLen = toLength(O.length);
+    var A = arraySpeciesCreate(O, 0);
+    flattenIntoArray(A, O, O, sourceLen, 0, depthArg === undefined ? 1 : toInteger(depthArg));
+    return A;
+  }
+});
+
+require('./_add-to-unscopables')('flatten');