Cleanup ref counts for SkCreateTypefaceForScript

After this checkin, SkCreateTypefaceForScript refs each typeface
that it creates before it returns it.  Additionally, all supported harfbuzz
codepoints are added to the unicode mapping array.  This patch also fixes a test crash (see bug)

Bug:6756432

Change-Id: Ida3276b76e745b817f9e63be54945e411516dd03
1 file changed