src/vs/editor/browser/editorExtensions.ts/Command/_registerMenuItem
class Command:	private _registerMenuItem(item: ICommandMenuOptions): void {
		MenuRegistry.appendMenuItem(item.menuId, {
			group: item.group,
			command: {
				id: this.id,
				title: item.title,
				icon: item.icon,
				precondition: this.precondition
			},
			when: item.when,
			order: item.order
		});
	}