Re: [css-houdini-drafts] [css-typed-om] el.attributeStyleMap.set('display', 'block') does not trigger attributeChangedCallback although style attribute changed. (#996)

This is what I observe:

```js
el.style.setProperty('display', 'none') // triggers attributeChangedCallback
el.attributeStyleMap.set('display', new CSSKeywordValue('block')) // does not trigger attributeChangedCallback
```

Is the `style` attribute officially supposed to change in the latter case? (I do see the style attribute change in Chrome element inspector)

Here's a full working code snippet to paste in console:

```js
class MyEl extends HTMLElement {
  static observedAttributes = ['style']
  attributeChangedCallback(attr, oldVal, newVal) { console.log(attr, oldVal, newVal) }
}

customElements.define('my-el', MyEl)

const el = document.createElement('my-el')
document.body.append(el)

console.log('--------------------')
el.style.setProperty('display', 'none')

console.log('--------------------')
el.attributeStyleMap.set('display', new CSSKeywordValue('block')) // no log

console.log('--------------------')
el.style.setProperty('display', 'none')

console.log('--------------------')
```

Output:

```
--------------------
style null display: none;
--------------------
--------------------
style display: block; display: none;
--------------------
```

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Received on Sunday, 2 August 2020 06:01:59 UTC