Currently it's not possible to resize the column containing the comments. Neither in Normal View, nor in Web view.
At least for the web view this feature will make sense. Especially when you're dealing with very long comments.
Steps to Reproduce:
1. Create a comment in a document
2. Try to resize the width of the comment column.
3. Actual: Does not work. It can only be disabled.
3. Expected: Resizing is possible.
User Profile Reset: Yes
There is already a small rectangular thing next to the comment column, that looks like it's exactly for that purpose.
Tested on: clean install
*** This bug has been marked as a duplicate of bug 73953 ***
Interesting. The other Bug did not show up on the bug search. Thank you for point ing out.