src/vs/editor/browser/viewParts/viewZones/viewZones.ts/ViewZones/_removeZone
class ViewZones:	private _removeZone(whitespaceAccessor: IWhitespaceChangeAccessor, id: string): boolean {
		if (this._zones.hasOwnProperty(id)) {
			const zone = this._zones[id];
			delete this._zones[id];
			whitespaceAccessor.removeWhitespace(zone.whitespaceId);

			zone.domNode.removeAttribute('monaco-visible-view-zone');
			zone.domNode.removeAttribute('monaco-view-zone');
			zone.domNode.domNode.parentNode!.removeChild(zone.domNode.domNode);

			if (zone.marginDomNode) {
				zone.marginDomNode.removeAttribute('monaco-visible-view-zone');
				zone.marginDomNode.removeAttribute('monaco-view-zone');
				zone.marginDomNode.domNode.parentNode!.removeChild(zone.marginDomNode.domNode);
			}

			this.setShouldRender();

			return true;
		}
		return false;
	}