Fix font family based fallback font selection

Introducing FontFaceCreationParams, used for creating a platform 
font face in the old way based on family, and in the fixed way, based on 
ttf filename and collection index.
Created a font based on Gardiner hieroglyphs font, same family name,
but two font files, one containing a bug glyph, one containing a cat
glyph. When the fonts are installed on the system, content_shell should
show both when opening the family-fallback-gardiner.html test case.
This works on Firefox, but on Chromium content_shell we used to only see
the bug symbol.

BUG=285303
R=eseidel,behdad,eae

Review URL: https://codereview.chromium.org/307243002

git-svn-id: svn://svn.chromium.org/blink/trunk@176765 bbb929c8-8fbe-4397-9dbb-9b2b20218538