UMD package: export MaterialUI variable

Currently to use Material-UI with codepen.io, JSFiddle… you have to write (see https://stackoverflow.com/q/50705423):

const { Button, Input } = window['material-ui'];

This is because the output name inside rollup.config.js is 'material-ui': https://github.com/mui-org/material-ui/blob/8013fdd36d40980ebb8f116f20e2843b781c0c39/packages/material-ui/scripts/rollup.config.js#L10

Instead it should be a name without -, something like 'MaterialUI':

const { Button, Input } = MaterialUI;

rollup.config.js example:

https://github.com/tkrotoff/react-form-with-constraints/blob/b64119bee6ab80c77417a9284a704b380b81bf5e/packages/react-form-with-constraints/rollup.config.js#L19-L27

Related issue: #7621

[oliviertassinari]

@tkrotoff This change sounds good to me. However, it’s a breaking change. We gonna need to bump the version to v2. I’m adding it into the milestone 👍

[oliviertassinari]

You can definitely open a pull request now on master. We will just wait before merging it 😃.