Merge to XFA: Cleanup: Do not check pointers before deleting them, part 2.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1195363002 .

(cherry picked from commit 21bf242a31eff79f754c5e9c3b41c52e33483bb0)

Review URL: https://codereview.chromium.org/1235753006 .