extensions/markdown-language-features/src/preview/topmostLineMonitor.ts/TopmostLineMonitor/getPreviousTextEditorLineByUri
class TopmostLineMonitor:	public getPreviousTextEditorLineByUri(resource: vscode.Uri): number | undefined {
		const scrollLoc = this._previousTextEditorInfo.get(resource);
		this._previousTextEditorInfo.delete(resource);
		return scrollLoc?.line;
	}