Width is constrained in some diffs

[samiraguiar]

I haven't been able to narrow down the issue, but sometimes the script narrows the width of the diff panels to about 60% of the available space.

For example, I experience the problem with this diff: https://github.com/AutoMapper/AutoMapper/pull/1245/files

Here's how it looks without the script in action:

And after:

In the second image, when the script runs the content shrinks and I get a lot of whitespace around it.