Italicize bug numbers of unconfirmed tickets in "Blocks/Depends on" field.

Copied from upstream global.css which decreases our CSS delta.
Upstream had a typo however which is also fixed in this commit. Typo has
been filed as https://bugzilla.mozilla.org/show_bug.cgi?id=926232

Bug: 54823
Change-Id: I5ed88fd121845cb68d834b3c54d85aa457bc67e3
Merge "Italicize bug numbers of unconfirmed tickets in "Blocks/Depends on" field."