更新前端静态网页获取方式，放弃使用后端获取api

frontend/node_modules/core-js-pure/internals/set-symmetric-difference.js

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+'use strict';
+var aSet = require('../internals/a-set');
+var SetHelpers = require('../internals/set-helpers');
+var clone = require('../internals/set-clone');
+var getSetRecord = require('../internals/get-set-record');
+var iterateSimple = require('../internals/iterate-simple');
+
+var add = SetHelpers.add;
+var has = SetHelpers.has;
+var remove = SetHelpers.remove;
+
+// `Set.prototype.symmetricDifference` method
+// https://tc39.es/ecma262/#sec-set.prototype.symmetricdifference
+module.exports = function symmetricDifference(other) {
+  var O = aSet(this);
+  var keysIter = getSetRecord(other).getIterator();
+  var result = clone(O);
+  iterateSimple(keysIter, function (e) {
+    if (has(O, e)) remove(result, e);
+    else add(result, e);
+  });
+  return result;
+};