st-texture-cache: Remove unused St.IconType.APPLICATION/DOCUMENT

No reason to have special handling for fallbacks that we can do (and do do)
in the JS.

https://bugzilla.gnome.org/show_bug.cgi?id=671656

src/st/st-types.h

@@ -44,9 +44,7 @@ typedef enum {
 
 typedef enum {
   ST_ICON_SYMBOLIC,
-  ST_ICON_FULLCOLOR,
-  ST_ICON_APPLICATION,
-  ST_ICON_DOCUMENT
+  ST_ICON_FULLCOLOR
 } StIconType;
 
 typedef enum {