extensions/markdown-language-features/src/util/tableOfContentsWatcher.ts/MdTableOfContentsWatcher/updateForResource
class MdTableOfContentsWatcher:	private async updateForResource(resource: vscode.Uri) {
		const existing = this._files.get(resource);
		const newToc = await this.tocProvider.get(resource);

		if (!existing || hasTableOfContentsChanged(existing.toc, newToc)) {
			this._onTocChanged.fire({ uri: resource });
		}

		this._files.set(resource, { toc: newToc });
	}