first

node_modules/core-js/internals/array-method-has-species-support.js

@@ -0,0 +1,20 @@
+'use strict';
+var fails = require('../internals/fails');
+var wellKnownSymbol = require('../internals/well-known-symbol');
+var V8_VERSION = require('../internals/engine-v8-version');
+
+var SPECIES = wellKnownSymbol('species');
+
+module.exports = function (METHOD_NAME) {
+  // We can't use this feature detection in V8 since it causes
+  // deoptimization and serious performance degradation
+  // https://github.com/zloirock/core-js/issues/677
+  return V8_VERSION >= 51 || !fails(function () {
+    var array = [];
+    var constructor = array.constructor = {};
+    constructor[SPECIES] = function () {
+      return { foo: 1 };
+    };
+    return array[METHOD_NAME](Boolean).foo !== 1;
+  });
+};