Merge to XFA: Convert CPDF_PatternMap to std::map.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1162123004.

(cherry picked from commit b3aa96cbee31e81d0a72a61027467a2713654499)

Review URL: https://codereview.chromium.org/1181573005.
3 files changed