Merge to XFA: Make the vast majority of JS headers private to src/javascript.

(cherry picked from commit 5b3d0208723f21c50b9922bdc500c9d78c359a25)
Original Review URL: https://codereview.chromium.org/1389783002 .

New changes to fix IWYU in:
  fpdfsdk/include/fpdfxfa/fpdfxfa_app.h
  xfa/include/fxfa/fxfa.h
  xfa/include/fxfa/fxfa_objectacc.h

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1388023003 .
47 files changed