public InlineToolbar.checkToolsState or trigger `checkState` in each selectionchange event

I wrote inline plugin to change style
```
input `123456` in editor;
First I chagne `123`to underline;
Then I select `3456` .In most editors ,If I set color to underline.`123456` Will be set to underline.
And when I select `4`,toolbar icon will become selected,and when I select `45` toolbar icon will become unselected.
```
But checkState only call once,so toolbar icon can't change with selectionchange
so I think `checkState` need to trigger multiple times when `selectionchange`