Revert 181541 "Merge FontPlatformDataHarfBuzz and FontPlatformData headers"

This reverts commit f2e0beaedaeaf15c509a2abd2c4fe598c4094bbd.

TBR=arv@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/546973004

git-svn-id: svn://svn.chromium.org/blink/trunk@181542 bbb929c8-8fbe-4397-9dbb-9b2b20218538