Button highlights sometimes not updated

Test 1

1. Write some text in Atto
2. Style the text so that at some places you combine multiple styles
   • List with bold items
   • Link that is italic
   • Bold + italic + underline
3. Make sure that when you move the cursor, the buttons are highlighted accordingly (each style should highlight its corresponding button)

Test 2

1. Add the following HTML using the HTML view

   <br>

   <b>test</b>

   <br><br>

2. Make sure the "Bold" button is only highlighted when the cursor is in the bold area, not at the beginning or the end of the content

Test 3

1. Select some text without style in the editor
2. Click the bold button and make sure the button is highlighted
3. Make a link
4. Select the link and click the unlink button
5. Make sure the unlink button is not highlighted

Test 4

1. Enter A LOT of text in the editor, and add many styles, lists, images, etc...
2. CTRL + A to select the whole content
3. Make sure the browser does not freeze, and the buttons are highlighted as you'd expect (note: MDL-45403)
4. Change your selection, and make sure the browser does not freeze