Add missing filter cards to zygote mod union table

Without filtering the cards, every object in the zygote is grayed
during the GC. This was deleted in a PS of previous CL.

GrayAllDirtyImmuneObjects goes from 1.974ms to 376.464us for CC on
N9 maps. This happens during the pause. This CL also fixes regression
in zygote PSS.

Bug: 29516968
Bug: 12687968

Change-Id: I42014e78b1de3ce9b2eefa3bd32f0d24e2ff71c6