External Babel configuration.

.babelrc

@@ -0,0 +1,12 @@
+{
+  "comments": false,
+  "compact": true,
+  "optional": [
+    "es7.asyncFunctions",
+    "es7.decorators",
+    "es7.functionBind",
+    "minification.deadCodeElimination",
+    "minification.inlineExpressions",
+    "runtime"
+  ]
+}

gulpfile.js

@@ -49,15 +49,7 @@ gulp.task(function buildCoffee () {
 gulp.task(function buildEs6 () {
   return src('**/*.js')
     .pipe(sourceMaps.init())
-    .pipe(babel({
-      compact: PRODUCTION,
-      comments: false,
-      optional: [
-        'es7.asyncFunctions',
-        'es7.decorators',
-        'runtime'
-      ]
-    }))
+    .pipe(babel())
     .pipe(sourceMaps.write('.'))
     .pipe(gulp.dest(DIST_DIR))
 })