Coc.nvim: 浮动窗口错误：“创建浮动窗口时出错：请求 nvim_open_win - 参数数量错误”

来自 CocInfo 的结果

## versions

vim version: NVIM v0.4.0-dev
node version: v8.9.0
coc.nvim version: 0.0.60
term: iTerm.app
platform: darwin

## Error messages
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5
## Output channel: watchman
[Info  - 09:45:52] watchman watching project: /Users/ctay20/code/termy-the-terminal
[Info  - 09:45:52] subscribing "**/[tj]sconfig.json" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:45:52] subscribing "**/package.json" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:45:52] subscribing "**/*.ts" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:45:52] subscribing "**/*.js" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] unsubscribe "20a54741-48d4-11e9-a9f7-9f67e0b40790" in: /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] unsubscribe "20a54740-48d4-11e9-a9f7-9f67e0b40790" in: /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] unsubscribe "2099fca0-48d4-11e9-a9f7-9f67e0b40790" in: /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] subscribing "**/[tj]sconfig.json" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] subscribing "**/package.json" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] subscribing "**/*.ts" in /Users/ctay20/code/termy-the-terminal
[Info  - 09:47:45] subscribing "**/*.js" in /Users/ctay20/code/termy-the-terminal

## Output channel: tsserver
[Info  - 09:47:45] Killing TS Server
[Info  - 09:47:45] Forking TSServer
PATH: /Users/ctay20/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:$HOME/.cargo/bin:/opt/X11/bin:/Users/ctay20/.cargo/bin:/Users/ctay20/.cargo/bin 
[Info  - 09:47:45] TSServer normal exit
[Info  - 09:47:45] TSServer log file: 
[Info  - 09:47:45] Started TSServer
{
  "path": "/Users/ctay20/code/termy-the-terminal/node_modules/typescript/lib",
  "_api": {
    "versionString": "3.3.3",
    "version": "3.3.3"
  }
}

描述错误
使用似乎与新浮动窗口功能相关的默认 Coc 功能时出错

重现
重现行为的步骤：

1. 下载neovim的master分支
2. 安装最新的 coc.nvim
3. 确保启用浮动窗口支持echo exists('##MenuPopupChanged') && exists('*nvim_open_win')应该返回 1
4. 打开.ts文件并在尝试自动完成时看到错误[vim-node-coc]: error on create floating window:request nvim_open_win - Wrong number of arguments: expecting 3 but got 5

截图