Unreviewed, rolling out r176789.
https://bugs.webkit.org/show_bug.cgi?id=139255

Broke the non Mac-WK2 builds (Requested by stavila on
#webkit).

Reverted changeset:

"Remove isSpecifiedFont boolean from FontDescription"
https://bugs.webkit.org/show_bug.cgi?id=139233
http://trac.webkit.org/changeset/176789

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@176790 268f45cc-cd09-0410-ab3c-d52691b4dbfc