Upgrade @babel/runtime-corejs2 to @babel/runtime-corejs3 (#142)

Author: ayu-exorcist

.babelrc

@@ -3,6 +3,8 @@
     [
       "@babel/preset-env",
       {
+        "corejs": 3,
+        "useBuiltIns": "usage",
         "exclude": [
           "transform-async-to-generator",
           "transform-regenerator"
@@ -21,7 +23,12 @@
     "@babel/plugin-proposal-class-properties",
     "@babel/plugin-proposal-object-rest-spread",
     "babel-plugin-lodash",
-    "@babel/plugin-transform-runtime"
+    [
+      "@babel/plugin-transform-runtime",
+      {
+        "corejs": 3
+      }
+    ]
   ],
   "env": {
     "coverage": {

package.json

@@ -78,6 +78,7 @@
     "chai": "^4.1.0",
     "coffee-script": "^1.11.1",
     "commander": "2.11.0",
+    "core-js": "^3.0.0",
     "cross-env": "6.0.3",
     "css-loader": "^5.0.1",
     "del": "5.1.0",
@@ -109,7 +110,7 @@
     "worker-loader": "^3.0.5"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "^7.0.0",
+    "@babel/runtime-corejs3": "^7.0.0",
     "chalk": "^2.4.2",
     "chokidar": "^3.5.2",
     "glob-parent": "5.1.2",