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

Also simplify CPDF_DocPageData::ReleaseIccProfile() since its first
argument is always null.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1149273004.

(cherry picked from commit a8a718c974210a919f2af0b099d540143cf330c6)

Review URL: https://codereview.chromium.org/1180613004.
4 files changed