chore: install cssbundling rails and set up compilation

spec/dummy/node_modules/yaml/dist/schema/common/null.js

@@ -0,0 +1,17 @@
+'use strict';
+
+var Scalar = require('../../nodes/Scalar.js');
+
+const nullTag = {
+    identify: value => value == null,
+    createNode: () => new Scalar.Scalar(null),
+    default: true,
+    tag: 'tag:yaml.org,2002:null',
+    test: /^(?:~|[Nn]ull|NULL)?$/,
+    resolve: () => new Scalar.Scalar(null),
+    stringify: ({ source }, ctx) => typeof source === 'string' && nullTag.test.test(source)
+        ? source
+        : ctx.options.nullStr
+};
+
+exports.nullTag = nullTag;