With the addition of the formatting toolbar for rich text editors, we noticed

that sometimes a horizontal grey bar would appear at the bottom of some

editors. For some reason, CodeMirror was setting their editor's overflow to

scroll, which would cause the grey scrollbar to appear. I was able to

reproduce this issue on Chrome (not on Firefox though), but was unable to

figure out why this was happening. This change fixes the bug by overriding

CodeMirror's CSS settings and forcing the overflow to always be auto.

Tested using all of the text input boxes on the review request page with

  various lengths of text.
Tested using the Add General Comment text input box and resizing the box,

  saw the overflow behaviour act the same as before.
Tested resizing my browser.
Tested in Chrome and Firefox.