🏗 fixing build errors using babel-upgrade (#197)

Author: Romain-web

.babelrc

@@ -1,12 +1,28 @@
 {
   "presets": [
-      [
-        "@babel/preset-env",
-        {
-          "modules": false
-        }
-      ],
-      "@babel/preset-stage-2"
+    [
+      "@babel/preset-env",
+      {
+        "modules": false
+      }
+    ],
+    "@babel/preset-flow"
   ],
-  "plugins": ["@babel/plugin-transform-flow-strip-types"]
+  "plugins": [
+    "@babel/plugin-transform-flow-strip-types",
+    "@babel/plugin-syntax-dynamic-import",
+    "@babel/plugin-syntax-import-meta",
+    "@babel/plugin-proposal-class-properties",
+    "@babel/plugin-proposal-json-strings",
+    [
+      "@babel/plugin-proposal-decorators",
+      {
+        "legacy": true
+      }
+    ],
+    "@babel/plugin-proposal-function-sent",
+    "@babel/plugin-proposal-export-namespace-from",
+    "@babel/plugin-proposal-numeric-separator",
+    "@babel/plugin-proposal-throw-expressions"
+  ]
 }

.nvmrc

@@ -0,0 +1 @@
+v8.12