src/vs/editor/browser/viewParts/scrollDecoration/scrollDecoration.ts/ScrollDecorationViewPart/constructor
class ScrollDecorationViewPart:	constructor(context: ViewContext) {
		super(context);

		this._scrollTop = 0;
		this._width = 0;
		this._updateWidth();
		this._shouldShow = false;
		const options = this._context.configuration.options;
		const scrollbar = options.get(EditorOption.scrollbar);
		this._useShadows = scrollbar.useShadows;
		this._domNode = createFastDomNode(document.createElement('div'));
		this._domNode.setAttribute('role', 'presentation');
		this._domNode.setAttribute('aria-hidden', 'true');
	}