revert core js version to old version

Author: 902seanryan

.babelrc

@@ -1,4 +1,5 @@
 {
+  "exclude": [ "node_modules/@babel/**", "node_modules/core-js/**" ],
   "presets": [
     [
       "@babel/preset-env",

dist/SpringRoll-Container-umd.js

@@ -12,6 +12,8 @@
   "devDependencies": {
     "@babel/core": "^7.4.3",
     "@babel/preset-env": "^7.4.3",
+    "@rollup/plugin-babel": "^5.2.0",
+    "@rollup/plugin-node-resolve": "^9.0.0",
     "babel-loader": "^8.0.5",
     "chai": "^4.2.0",
     "dotenv": "^7.0.0",
@@ -46,7 +48,7 @@
   "dependencies": {
     "@babel/polyfill": "^7.4.3",
     "bellhop-iframe": "^3.2.0",
-    "core-js": "^3.0.1",
+    "core-js": "^2.6.5",
     "whatwg-fetch": "^3.0.0"
   },
   "keywords": [

dist/SpringRoll-Container-umd.js.map

@@ -1,6 +1,7 @@
 const { eslint } = require('rollup-plugin-eslint');
 const { terser } = require('rollup-plugin-terser');
 
+
 const base = {
   plugins: [
     // @ts-ignore