Add a check to prevent re-selecting same range

[sohnryang]

This fixes #2714.

[the-mikedavis]

I gave this a try and it looks like there's an edge-case when we expand to the root node: we hit A-o until we are at the root node and then A-i doesn't change the selection.

Instead, I think we can compare the selection returned by the object::expand_selection line and current_selection. We should only push current_selection and call doc.set_selection if the current_selection isn't equal to the expanded selection

[sohnryang]

Fixed!

[the-mikedavis]

Works great, thanks for the fix!