DOM distiller might have some assumptions that rely on Chrome-specific behavior. See  issue 873298  and  issue 873291  for example.

Most of the failures in Firefox are due to switched order of weight/height attributes, which should be fine. The other failures are:

TableClassifierTest.testBorderAroundCells:
Expected=DATA
Actual  =LAYOUT

TreeCloneBuilderTest.testCloneElement:
Expected=<div dir="auto"></div>
Actual  =<div dir="ltr"></div>

TableClassifierTest.testBorderAroundCells might be the most worrysome failure.