Tui.editor: option height: 'auto' displays horizontal scrolling bar in textarea

[bricepepin]

Version

1.1.1

Test Environment

Windows 7 and Chrome 66

Current Behavior

If you set the option height: 'auto' to the editor, you can see an horizontal scrolling bar in the middle of the textarea.

Expected Behavior

Hide the scrolling bar.

This can be done with something like this :

```css
.CodeMirror-scroll {
min-height: 166px;
}
````

[sohee-lee7]

[gregroyal]

Might also be related to the editor not initializing correctly if starting in markdown mode.
I found something if its in an element with display: none theres initialization issues
Checkout https://github.com/codemirror/CodeMirror/issues/798

[ibocon]

I found cause of this issue.

min-height: 145px; should also apply to <div class="CodeMirror-scroll" ... />.