Error when font family name include space

[plantain-00]

Steps for Reproduction

1. Visit [quilljs.com, jsfiddle.net, codepen.io]](https://quilljs.com/docs/formats/)
2. Input 'a'
3. Open browser console, input:

let Font = Quill.import('formats/font')
Font.whitelist = ['Source Han Sans CN']
quill.formatText(0,1,'font','Source Han Sans CN')

Expected behavior:

No Error

Actual behavior:

 Failed to execute 'add' on 'DOMTokenList': The token provided ('ql-font-Source Han Sans CN') contains HTML space characters, which are not valid in tokens.
    at e.add (https://cdn.quilljs.com/1.3.6/quill.min.js:7:88192)
    at t.attrib

Platforms:

Include browser, operating system and respective versions

Version:

1.3.6

[toothbrush7777777]

Use dashes instead:

let Font = Quill.import('formats/font')
Font.whitelist = ['source-han-sans-cn']
quill.formatText(0,1,'font','source-han-sans-cn')

.ql-font-source-han-sans-cn {
  font-family: 'Source Han Sans CN';
}

[benbro]

Related https://github.com/quilljs/quill/issues/3292