expect style to be available

For the `d.style(…)` function, we expect a node that has a `style`
attribute. We don't care what kind of node that it is.

Author: RobinMalfait

packages/@headlessui-react/src/utils/disposables.ts

@@ -56,7 +56,7 @@ export function disposables() {
       })
     },
 
-    style(node: HTMLElement, property: string, value: string) {
+    style(node: ElementCSSInlineStyle, property: string, value: string) {
       let previous = node.style.getPropertyValue(property)
       Object.assign(node.style, { [property]: value })
       return this.add(() => {

packages/@headlessui-react/src/utils/dom.ts

@@ -31,6 +31,10 @@ export function isHTMLorSVGElement(element: unknown): element is HTMLOrSVGElemen
   return isElement(element) && 'tabIndex' in element
 }
 
+export function hasInlineStyle(element: unknown): element is ElementCSSInlineStyle {
+  return isElement(element) && 'style' in element
+}
+
 export function isHTMLIframeElement(element: unknown): element is HTMLIFrameElement {
   return isHTMLElement(element) && element.nodeName === 'IFRAME'
 }