Merge to XFA: Extern in .cpp file is a code smell, part 2.

(cherry picked from commit c3f4894a6862c74b9ab32b4ec38c531de6ecd83c)
Original Review URL: https://codereview.chromium.org/1298393003 .

Fixed IWYU in core/src/fpdftext/text_int.h exposed by new inclusion.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1294933008 .
27 files changed