[change] export ES modules by default

ES modules are the default package export. Commonjs modules are exported
from 'dist/cjs'. Modern bundlers like webpack can consume ES modules.
The addition of the `sideEffects:false` to the `package.json` helps
webpack tree-shaking modules.

packages/benchmarks/webpack.config.js

@@ -32,7 +32,7 @@ module.exports = {
           options: {
             cacheDirectory: false,
             presets: babelPreset,
-            plugins: ['react-native-web', 'styled-jsx/babel']
+            plugins: ['styled-jsx/babel']
           }
         }
       }
@@ -43,5 +43,10 @@ module.exports = {
       analyzerMode: 'static',
       openAnalyzer: false
     })
-  ]
+  ],
+  resolve: {
+    alias: {
+      'react-native': 'react-native-web'
+    }
+  }
 };

packages/react-native-web/package.json

@@ -2,7 +2,9 @@
   "name": "react-native-web",
   "version": "0.6.1",
   "description": "React Native for Web",
-  "main": "dist/index.js",
+  "module": "dist/index.js",
+  "main": "dist/cjs/index.js",
+  "sideEffects": false,
   "files": [
     "dist",
     "jest",