Looks like the 32bit and 64bit version are off by just one pixel.
Committed r59262: <http://trac.webkit.org/changeset/59262>
Accidentally closed via webkit-patch.
Committed r59398: <http://trac.webkit.org/changeset/59398>
*** Bug 36491 has been marked as a duplicate of this bug. ***
Committed r65378: <http://trac.webkit.org/changeset/65378>
Yet another test seems to be suffering of the same problem.
Skipped at the moment.
Committed r81656: <http://trac.webkit.org/changeset/81656>
*** This bug has been marked as a duplicate of bug 72254 ***