When the reviver returns undefined, the property in question must be deleted
even for arrays.  So far this only happened for non-array objects.

Also change the property enumeration to be spec-conformant, which is observable when the reviver modifies its "this" object directly.  There are a few further issues that need to be addressed in a separate CL.

R=yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1506933003

Cr-Commit-Position: refs/heads/master@{#32750}