Disable handle zapping on 4.3 branch

BUG=
LOG=n
TBR=vogelheim@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1058893002

Cr-Commit-Position: refs/branch-heads/4.3@{#2}
Cr-Branched-From: f5c0a23a-refs/heads/4.3.61@{#1}
Cr-Branched-From: 0a7d4f49-refs/heads/master@{#27508}