Fix some issues found by coverity scans on Node.js

BUG=
[email protected], [email protected]

Review-Url: https://codereview.chromium.org/2098523002
Cr-Original-Commit-Position: refs/heads/master@{#401981}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: bdb1a680c245c40132f492ec7f0e5b4dcb48210f
4 files changed