Merge to XFA: wstring allocations waste up to 7 wasted bytes.

Original Review URL: https://codereview.chromium.org/1399983003 .
(cherry picked from commit 6eeffab789800e2afa1b9d10de70c9116db32355)

R=thestig@chromium.org
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/1399893003 .
1 file changed