EffectPhis can cause a cycle in a TurboFan graph. We delay the
processing of EffectPhis in the Int64Lowering to break these cycles. We
do the same already for Phis.

R=titzer@chromium.org
BUG=v8:5518
TEST=unittests/Int64LoweringTest.EffectPhiLoop

Review-Url: https://codereview.chromium.org/2428583002
Cr-Commit-Position: refs/heads/master@{#40378}