[core] Add support for Webpack 2/Rollup tree shaking (#5545)

* Add support Webpack 2/Rollup tree shaking

* Add custom `babel-es2015-preset`, Transpile `index.js` file with `babel`

* Move `material-ui-babel-es2015-preset` from `packages` to `tools`

.babelrc

@@ -1,5 +1,5 @@
 {
-  "presets": ["es2015", "stage-1", "react"],
+  "presets": ["./tools/material-ui-babel-preset-es2015", "stage-1", "react"],
   "plugins": [
     ["transform-replace-object-assign", "simple-assign"],
     "transform-dev-warning"
@@ -20,7 +20,7 @@
       "plugins": [
         "transform-runtime",
         ["transform-react-remove-prop-types", {"mode": "wrap"}]
-      ],
+      ]
     }
   }
 }

package.json

@@ -21,7 +21,8 @@
   },
   "homepage": "http://material-ui.com/",
   "scripts": {
-    "build": "npm run build:icon-index && npm run build:babel && npm run build:copy-files",
+    "build": "npm run build:icon-index && npm run build:babel && npm run build:copy-files && npm run build:index",
+    "build:index": "BABEL_ENV=es babel ./src/index.js --out-file ./build/index.es.js",
     "build:icon-index": "babel-node ./scripts/icon-index-generator.js",
     "build:babel": "NODE_ENV=release babel ./src --out-dir ./build --ignore spec.js",
     "build:copy-files": "babel-node ./scripts/copy-files.js",

scripts/copy-files.js

@@ -63,6 +63,8 @@ function createPackageFile() {
       version,
       description,
       main: './index.js',
+      module: './index.es.js',
+      'jsnext:main': './index.es.js',
       keywords,
       repository,
       license,

tools/material-ui-babel-preset-es2015.js

@@ -0,0 +1,11 @@
+const es2015 = require('babel-preset-es2015').buildPreset;
+
+const ENV = process.env.BABEL_ENV;
+
+module.exports = {
+  presets: [
+    [ es2015, {
+      modules: ENV === 'es' ? false : 'commonjs'
+    } ],
+  ],
+};