src/vs/editor/browser/editorDom.ts/RefCountedCssRule/constructor
class RefCountedCssRule:	constructor(
		public readonly key: string,
		public readonly className: string,
		_containerElement: HTMLElement | undefined,
		public readonly properties: CssProperties,
	) {
		this._styleElement = dom.createStyleSheet(
			_containerElement
		);

		this._styleElement.textContent = this.getCssText(this.className, this.properties);
	}