Add umdNamedDefine: true to webpack UMD output

Summary:
The `clientParamBuilder.bundle.js` UMD bundle uses an anonymous `define()` call, which conflicts with RequireJS on pages like Magento 2 checkout. When RequireJS is present, it intercepts the anonymous `define([], factory)` instead of letting the module register on `window`, causing `clientParamBuilder` to be undefined and breaking checkout JS.

Adding `umdNamedDefine: true` changes the output from `define([], t)` to `define('clientParamBuilder', [], t)`, which prevents RequireJS from hijacking the module as an unresolvable anonymous definition.

Fixes: #28
Ref: facebook/GoogleTagManager-WebTemplate-For-FacebookPixel#31

Reviewed By: ppwang-sa

Differential Revision: D105386494

fbshipit-source-id: 0459a19bc096f8ad31f57bbc7db03d6a0a0994b9

Author: haretonj

client_js/webpack.config.js

@@ -18,6 +18,7 @@ module.exports = {
     filename: `[name].bundle.js`,
     library: `[name]`,
     libraryTarget: `umd`,
+    umdNamedDefine: true,
   },
   resolve: {
     extensions: [`.js`],