Merge FontPlatformDataHarfBuzz into FontPlatformData

From WebKit legacy we have two redundant copies of this file.
In order for switching shapers on mac, we need to fuse these files again. 
This is part two of the merge,
after the headers were merged in r181655 / ad011a9df.

BUG=334269

R=eae

Review URL: https://codereview.chromium.org/550083005

git-svn-id: svn://svn.chromium.org/blink/trunk@181754 bbb929c8-8fbe-4397-9dbb-9b2b20218538