drop node@4 support

.travis.yml

@@ -1,5 +1,4 @@
 language: node_js
 node_js:
-  - "4"
   - "6"
   - "node"

package.json

@@ -1,16 +1,18 @@
 {
   "name": "icss-utils",
-  "version": "3.0.1",
+  "version": "4.0.0",
   "description": "ICSS utils for postcss ast",
-  "main": "lib/index.js",
+  "main": "src/index.js",
+  "engines": {
+    "node": ">= 6"
+  },
   "files": [
-    "lib"
+    "src"
   ],
   "scripts": {
-    "build": "babel --out-dir lib src",
     "test": "jest --coverage",
     "precommit": "lint-staged",
-    "prepublish": "yarn test && yarn run build"
+    "prepublish": "yarn test"
   },
   "lint-staged": {
     "*.js": [
@@ -28,18 +30,6 @@
     },
     "extends": "eslint:recommended"
   },
-  "babel": {
-    "presets": [
-      [
-        "env",
-        {
-          "targets": {
-            "node": 4
-          }
-        }
-      ]
-    ]
-  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/css-modules/icss-utils.git"
@@ -60,9 +50,6 @@
     "postcss": "^7.0.5"
   },
   "devDependencies": {
-    "babel-cli": "^6.24.1",
-    "babel-jest": "^20.0.3",
-    "babel-preset-env": "^1.5.2",
     "eslint": "^4.0.0",
     "husky": "^0.13.4",
     "jest": "^20.0.4",