User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0 Build ID: 20171107220115 Steps to reproduce: 1. Get a mouse with a wheel without "click-to-click" scrolling (a wheel which has momentum), like the Logitech Anywhere MX 2 mouse that I have. 2. Go to a long web page. 3. Start scrolling with the mouse (not the trackpad). 4. While the page is still scrolling, press the Cmd key. Actual results: The page zooms in or out (depending on the direction of the scroll). Expected results: The page should keep being scrolled. (Note that the issue is similar to #1218073, but that this is with a mouse instead of a trackpad).

To solve this issue, I think that zoom control should be active only when the Cmd/Ctrl key is pressed and then when scroll starts. It should not be active while the page is still being scrolled and the Cmd/Ctrl key is pressed at the same time.