Style object must include dashed properties

[dead-claudia]

Describe the bug
Per spec, all supported CSS properties that are not custom properties must have corresponding dashed properties on elem.style. This includes vendor-prefixed properties like -webkit-*.

These properties appear missing.

To Reproduce

const { Window } = require('happy-dom')
const window = new Window()

window.document.body.innerHTML = '<p>Hello world</p>'
const element = window.document.querySelector("p")

// mutate hyphenated property
element.style["font-size"] = "10px"

// print value
console.log(element.style.getProperty("font-size"))

Expected behavior
It to print the value that was set

Additional context
Resulted in MithrilJS/mithril.js#2989 (comment) being filed.

I don't have version or OS info, but it appears it's likely the latest version if https://github.com/capricorn86/happy-dom/blob/master/packages/happy-dom/src/css/declaration/CSSStyleDeclaration.ts is the only relevant file. @kfule may have more info as he's the one who reported it as an example.