move most of SkFontHost to private (preceeding making it all private)

In this change, have to accomodate PDF wanting to call openStream and advancedMetrics
Review URL: https://codereview.chromium.org/12739006

git-svn-id: http://skia.googlecode.com/svn/trunk@8156 2bbb7eff-a529-9590-31e7-b0007b416f81
9 files changed