fix tests

package.json

@@ -39,7 +39,6 @@
     "browser-sync": "^2.26.7",
     "connect-history-api-fallback": "^1.6.0",
     "copy-webpack-plugin": "^5.0.3",
-    "core-js": "^3.1.3",
     "css-loader": "^3.0.0",
     "dart-sass": "^1.21.0",
     "eslint": "^5.16.0",
@@ -53,11 +52,13 @@
     "html-webpack-plugin": "^3.2.0",
     "http-proxy-middleware": "^0.19.1",
     "http-server": "^0.11.1",
+    "identity-obj-proxy": "^3.0.0",
     "imagemin-webpack-plugin": "^2.4.2",
     "jest": "^24.7.1",
     "lerna": "^3.15.0",
     "mini-css-extract-plugin": "^0.7.0",
     "minimist": "^1.2.0",
+    "mutation-observer": "^1.0.3",
     "optimize-css-assets-webpack-plugin": "^5.0.1",
     "ora": "^3.4.0",
     "postcss": "^7.0.17",