* Minification is done by uglify, so disable that in the media build.
* The webpack boilerplate has changed, which explains the changes in the build files.
* ModuleConcatenationPlugin is enable by default for production builds so we don't have to specify that ourselves.
Merge notes: In `trunk` uglify isn't run on the media files after webpack, so webpack does need to do that. Newer webpack versions use `terser-webpack-plugin` as the default minification. Use the `uglifyjs-webpack-plugin` plugin to maintain the same behavior as before. We can look into terser as a minifier later.
Merges [43688] to trunk.
See #45065.
git-svn-id: https://develop.svn.wordpress.org/trunk@44111 602fd350-edb4-49c9-b593-d223f7449a82
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