Remove/replace minified webpack plugin code in xdLocalStoragePostMessageApi.min.js

[SamClayton]

Appears to be a Webpack plugin that pairs with iframe.html to facilitate LocalStorage access. Unclear why. Minified js is unmaintainable, so best to replace it. At minimum, can a readable version be compiled by Webpack as part of build proc?

[SamClayton]

Dupe of #12 . Merge