Merge to XFA: Fix more sign comparison errors.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1290383003 .

(cherry picked from commit 9494421208674d2c57a9f864d342f017c0b20902)

Review URL: https://codereview.chromium.org/1288603006 .
4 files changed