Created attachment 119843 [details]
This tests some pattern placement oddities caused by rounding.
The chessboard fill should end AT a field boundary, no cropped parts of a square
should be visible at any side of the pattern. The square boundaries should not
be affected by zooming.
The top square should be a one-pixel stroke with no bleed of red or green into
the adjacent pixels.
Firefox 8 and Opera 11.60 both display the pattern properly. Opera does bleed green in the rendering of the top square, Firefox does not have that problem.
The issue is caused by the rounding done in SVGImageBufferTools::createImageBuffer and lack of correction for the location of the buffer rectangle. The same type of problem appears in bug 73643, but patterns require a different treatment to avoid bleeding pixels under the pattern.
Confirmed in Safari 5.1.7.