Comment 114 for bug 209509

Philippe, the test case has a background-color of #FFF applied to it in CSS. If the test case had a black background on the form and the CSS had not been written to compensate, the writing would be invisible. That is exactly as now (not) being seen on any dark-backgrounded sites with a file upload... unless browsing with something other than FF22/23, in which case it continues to be as readable as ever. Inside a form input is light, or dark, and you set CSS to contrast with that background. If 'input' text starts being written outside the input box, which is often dark when the input box is light, and vice versa, the contrast will often be dramatically reduced to the point that you cannot see the text.
Summary - you need to show text against the same background tone for an input[file] as for all other inputs, default being white. You can't rely on having the same background outside of a box as inside.