Adding upstream version 5.2.3+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

js/tests/integration/rollup.bundle.js

@@ -0,0 +1,24 @@
+/* eslint-env node */
+
+const { babel } = require('@rollup/plugin-babel')
+const { nodeResolve } = require('@rollup/plugin-node-resolve')
+const replace = require('@rollup/plugin-replace')
+
+module.exports = {
+  input: 'js/tests/integration/bundle.js',
+  output: {
+    file: 'js/coverage/bundle.js',
+    format: 'iife'
+  },
+  plugins: [
+    replace({
+      'process.env.NODE_ENV': '"production"',
+      preventAssignment: true
+    }),
+    nodeResolve(),
+    babel({
+      exclude: 'node_modules/**',
+      babelHelpers: 'bundled'
+    })
+  ]
+}