Add Babel plugin for closure elimination (disabled for now).

.babelrc

@@ -2,14 +2,17 @@
   "comments": false,
   "compact": true,
   "optional": [
-    // This options are experimental for now and may (will) break the
-    // code.
+    // Experimental features.
+    // "minification.constantFolding",
     // "minification.deadCodeElimination",
-    // "minification.inlineExpressions",
 
     "es7.asyncFunctions",
     "es7.decorators",
     "es7.functionBind",
     "runtime"
+  ],
+  "plugins": [
+    // Disabled due to https://github.com/codemix/babel-plugin-closure-elimination/issues/1
+    // "closure-elimination"
   ]
 }

package.json

@@ -84,6 +84,7 @@
   },
   "devDependencies": {
     "babel-eslint": "^3.1.9",
+    "babel-plugin-closure-elimination": "0.0.1",
     "chai": "~2.1.2",
     "gulp": "git://github.com/gulpjs/gulp#4.0",
     "gulp-babel": "^5",