Clean up CFGAS_GEFont

Removed some unused method, named files properly, cleaned up a bit.

Review-Url: https://codereview.chromium.org/2524493002
diff --git a/xfa/fxfa/app/xfa_fontmgr.cpp b/xfa/fxfa/app/xfa_fontmgr.cpp
index 857c1d5..e83cf48 100644
--- a/xfa/fxfa/app/xfa_fontmgr.cpp
+++ b/xfa/fxfa/app/xfa_fontmgr.cpp
@@ -13,7 +13,7 @@
 #include "core/fpdfapi/font/cpdf_font.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
-#include "xfa/fgas/font/fgas_gefont.h"
+#include "xfa/fgas/font/cfgas_gefont.h"
 #include "xfa/fxfa/xfa_ffapp.h"
 #include "xfa/fxfa/xfa_ffdoc.h"