Check out this JSFiddle: http://jsfiddle.net/annam/kkraLbhf/ Focus on the input and start typing. the document scrolls to where the input would appear, if the iframe was not under transform:scale(); Also happens to me as soon as you click to focus the input in some cases, though not consistently.
happens in safari and chrome on both mac and windows.
<rdar://problem/19471657>
Note: the fiddle needs to have the -webkit- prefix added to the transform functions to work in Safari.