Back button closes newly created tabs

[CodedGames]

In Safari if you just opened a new tab (for example to view a picture from Reddit) and then hit the back button it would close the new tab and show the previously viewed tab. Example: https://gyazo.com/7c76267eddbb9af9c4ac8997d2d8ea0b

In Firefox the back button does nothing if there is nothing to go back to. I really wish this function was in Firefox.

[CodedGames]

Unfortunately I have switched back to Safari and it's mostly because Firefox is missing this feature. Even when the plugin worked it still wasn't quite as good as the Safari implementation. 

Also one thing to note is this function is not exactly the same as closing a tab. Because if you close the tab in the video it will always show the rightmost tab. But in Safari the previous tab you were on could be any of them and the back button would take you back to whichever one you were looking at. So this isn't just slightly a different method to how it works in Firefox it's a feature completely missing in Firefox