Bug 1058900 - [email] pinch/zoom mitigations

Whoops, the thought was not completed.  I definitely would never put a comment in saying stuff like "I wrote this code, suckahs!"  I kept vacillating between calling attention to the fact that I wasn't sure if this was doing anything and being afraid to remove it "because I did most of the development and testing where things worked with the overflow: hidden present and I'm worried about removing it now".