This is really an issue with the HTML in our test runner. Attached patch guarantees that the frame used for the test page gets the top-left 500x500 pixels of the window, which should eradicate this kind of errors. And also, our HTML was definitely broken, with a <table> element that never was closed, so this patches fixes it and indents this code.

Try: http://tbpl.allizom.org/?tree=Try&usebuildbot=1&rev=fffeac58b3e7