Toggle Block Comment selection is inconsistent with multiple line selections

[njx]

1. Open a JS file
2. Create two cursors (using Cmd-click) on two lines that aren't adjacent
3. Ctrl-L to select both lines
4. Cmd-Alt-/ to block comment

Result: The first selection expands to include the end comment line, which it shouldn't. The second selection is correct.

[njx]

This is probably a bug in how the comment logic was modified to handle multiple selections, not a bug in the comment logic itself. It reproduces both in master and in #7135.

/cc @TomMalbran - don't think you need to do anything about this but thought you might be interested.

[pthiess]

@TomMalbran -- I took the liberty to assign this to you without knowing whether you're truly interested, please feel free to reassign to @njx anytime.

Thanks a ton!

[TomMalbran]

@njx wrote the part that made it work with multiple cursors and I don't fully understand how it works. I would need to understand the code first. I guess it might be better if @njx fixed this.