Diff lines indented incorrectly #397

It looks like a GitHub update has caused the easier copy/paste feature from #282 to start indenting diffs incorrectly in some places.

For instance, in the diff of #282 itself:

<img width="127" alt="screen shot 2017-05-03 at 10 02 36" src="https://cloud.githubusercontent.com/assets/1935696/25652450/91491f46-2fe8-11e7-8df9-fa81a6cde1d7.png">

https://github.com/sindresorhus/refined-github/pull/282/files

The td selector is not vertically aligned with the closing curly bracket.

However, as a counterexample (to show that it doesn't always happen everywhere), the if conditional also in this pull request does line up correctly:

<img width="111" alt="screen shot 2017-05-03 at 10 30 22" src="https://cloud.githubusercontent.com/assets/1935696/25653076/9aa1d49a-2feb-11e7-90a0-4c4aab34ebc4.png">

cc @jacobbearden