Content gets duplicated for macros that can be inline edited, after deleting and undoing the deletion of content

Steps: 

• In an empty WYSIWYG area, open the 'Select Macro' modal and select 'Info' macro
• Because the content is mandatory, write 'AB', press 'Submit'
• You will get a block macro that contains 'AB' inside an info box
• The mouse cursor is before the 'AB', like '|AB'. 
• Change the cursor to be after the 'AB', like 'AB|'
• Delete all the letters 'AB', then write some other characters 'DC'
• Then press from your keyboard: Command+A (to select the whole text)
• Then press 'Delete' - everything will be delete
• Then press Command+Z (to undo the deletion)
• BUG: you will get 2 {{info macros}}
• BUG: if at this state you press multiple Command+Z, you will get also other states of your browsers history.

 
Tested on Chrome 71, with Mac OS.