src/vs/editor/browser/view/viewLayer.ts/ViewLayerRenderer/_removeLinesBefore
class ViewLayerRenderer:	private _removeLinesBefore(ctx: IRendererContext<T>, removeCount: number): void {
		for (let i = 0; i < removeCount; i++) {
			const lineDomNode = ctx.lines[i].getDomNode();
			if (lineDomNode) {
				this.domNode.removeChild(lineDomNode);
			}
		}
		ctx.lines.splice(0, removeCount);
	}