e.g.,

for (var k in o) {
  if (!o.hasOwnProperty(k)) continue;
  ...
}

without enumerable properties on the prototype chain of o.

BUG=

Committed: https://crrev.com/dec80752eb344dfeb85588e61ac0afd22b11aadb
Cr-Commit-Position: refs/heads/master@{#34379}

Review URL: https://codereview.chromium.org/1742253002

Cr-Commit-Position: refs/heads/master@{#34405}