extensions/typescript-language-features/src/tsServer/bufferSyncSupport.ts/BufferSyncSupport/ensureHasBuffer
class BufferSyncSupport:	public ensureHasBuffer(resource: vscode.Uri): boolean {
		if (this.syncedBuffers.has(resource)) {
			return true;
		}

		const existingDocument = vscode.workspace.textDocuments.find(doc => doc.uri.toString() === resource.toString());
		if (existingDocument) {
			return this.openTextDocument(existingDocument);
		}

		return false;
	}