Update babel procedure in gulp

Author: lvaccaro

.babelrc

@@ -1,18 +1,21 @@
 // with options
 {
   "presets": [
-    [ "env", {
-      "browsers": [
+    [ "@babel/preset-env", {
+      "targets": [
         "last 2 versions",
         "ie >= 9",
         "safari >= 8",
         "firefox >= 40",
         "chrome >= 40",
-        "chromium >= 40"
+        "electron >= 6"
         ],
       "modules": false,
       "debug": true,
-      "useBuiltIns": true
+      "useBuiltIns": "entry"
     }]
+  ],
+  "plugins": [
+    "@babel/plugin-transform-classes"
   ]
-}
+}

gulpfile.js

@@ -44,7 +44,7 @@ gulp.task('index', () => {
   }
   return gulp.src('./')
     .pipe(exec('./node_modules/browserify/bin/cmd.js --standalone "OpenTimestamps" index.js > ./dist/opentimestamps.es6.js', options))
-    .pipe(exec('./node_modules/babel-cli/bin/babel.js ./dist/opentimestamps.es6.js -o ./dist/opentimestamps.js', options))
+    .pipe(exec('./node_modules/.bin/babel ./dist/opentimestamps.es6.js -o ./dist/opentimestamps.js', options))
     .pipe(exec.reporter(reportOptions))
 
     /* NOTE: babelify run babel with .babelrc file, but doesn't convert the code

package.json

@@ -19,9 +19,8 @@
   "devDependencies": {
     "@babel/cli": "^7.8.3",
     "@babel/core": "^7.8.3",
-    "babel-plugin-transform-es2015-classes": "^6.24.1",
-    "babel-preset-env": "^1.6.1",
-    "babel-preset-es2015": "^6.24.1",
+    "@babel/plugin-transform-classes": "^7.8.3",
+    "@babel/preset-env": "^7.8.3",
     "babelify": "^7.3.0",
     "browserify": "13.0.0",
     "faucet": "0.0.1",