Consider case when 'core-js' is located in 'babel-polyfill' root (#181)

* Rdesign Advanced Customization examples to use Neutrino v5 fashion

* Fix cases when there are several 'core-js' instances in the project

* Add 'core-js' alias and lock 'babel-polyfill' version

* Spaces instead of tabs

* Use `dirname` instead of `join`

* Correct hierarchy indentation

packages/neutrino-preset-web/index.js

@@ -12,7 +12,7 @@ const clean = require('neutrino-middleware-clean');
 const minify = require('neutrino-middleware-minify');
 const loaderMerge = require('neutrino-middleware-loader-merge');
 const namedModules = require('neutrino-middleware-named-modules');
-const { join } = require('path');
+const { join, dirname } = require('path');
 const { path, pathOr } = require('ramda');
 
 const MODULES = join(__dirname, 'node_modules');
@@ -99,6 +99,10 @@ module.exports = (neutrino) => {
       .chunkFilename('[id].[chunkhash].js')
       .end()
     .resolve
+      .alias
+        // Make sure 2 versions of "core-js" always match in package.json and babel-polyfill/package.json
+        .set('core-js', dirname(require.resolve('core-js')))
+        .end()
       .modules
         .add('node_modules')
         .add(neutrino.options.node_modules)

packages/neutrino-preset-web/package.json

@@ -16,7 +16,8 @@
   "bugs": "https://github.com/mozilla-neutrino/neutrino-dev/issues",
   "dependencies": {
     "babel-plugin-syntax-dynamic-import": "^6.18.0",
-    "babel-polyfill": "^6.23.0",
+    "babel-polyfill": "6.23.0",
+    "core-js": "^2.4.0",
     "babel-preset-env": "^1.2.2",
     "exports-loader": "^0.6.4",
     "imports-loader": "^0.7.1",