Replace babel-preset-es2015 with babel-preset-env configured for the last 6 browser versions to improve speed and performance

.babelrc

@@ -0,0 +1,11 @@
+{
+    presets: [
+        [
+            "env", {
+                "targets": {
+                    "browsers": [ "last 6 versions" ]
+                }
+            }
+        ]
+    ]
+}

gulpfile.js

@@ -79,7 +79,7 @@ function processJavaScript(ouputFilename, inputFiles, es6) {
         .pipe(gPlumber(plumberError))
         .pipe(gConcat(ouputFilename + ".js"));
 
-    if (es6) { javascript.pipe(gBabel({ presets: [ "es2015" ] })); }
+    if (es6) { javascript.pipe(gBabel()); }
     if (prod) { javascript.pipe(gStripDebug()).pipe(gUglify()); }
     return javascript.pipe(gulp.dest("public/js/"));
 }

package.json

@@ -8,9 +8,9 @@
     "gulp-livereload": "^3.8.1"
   },
   "dependencies": {
-    "autoprefixer": "^7.1.4",
+    "autoprefixer": "^7.1.6",
     "babel-core": "^6.26.0",
-    "babel-preset-es2015": "^6.24.1",
+    "babel-preset-env": "^1.6.1",
     "gulp": "^3.9.1",
     "gulp-babel": "^7.0.0",
     "gulp-concat": "^2.6.1",