-what happened: Inconsistent behaviour between Chrome/Safari/Edge and Firefox when pressing Up/Down/left/right arrow keys. When there is a scroll bar the sphere object will move up/down when pressing Up/Down arrow keys, however, in Chrome/safari/Edge that will also make the webpage scroll.

Chrome/Safari/Edge: Up/Down/left/right arrow keypresses are handled by both Unity and browser
Firefox: Up/Down/left/right arrow keypresses are only handled by Unity

-repro:
--Build and Run for WebGL (see new attached move script)
--resize browser so you have the content tab with a horizontal and/or vertical scroll bar
--press up/down/left/right keys
--NOTICE when running in Chrome/Safari/Edge the sphere and the page itself move up and down

There is also a forum thread here:
http://forum.unity3d.com/threads/browser-input-working-together-with-webgl.363398/