src/vs/base/browser/ui/menu/menu.ts/Menu/initializeOrUpdateStyleSheet
class Menu:	private initializeOrUpdateStyleSheet(container: HTMLElement, style: IMenuStyles): void {
		if (!this.styleSheet) {
			if (isInShadowDOM(container)) {
				this.styleSheet = createStyleSheet(container);
			} else {
				if (!Menu.globalStyleSheet) {
					Menu.globalStyleSheet = createStyleSheet();
				}
				this.styleSheet = Menu.globalStyleSheet;
			}
		}
		this.styleSheet.textContent = getMenuWidgetCSS(style, isInShadowDOM(container));
	}