[os2] Move typometrics detection logic to the table (#1465)

diff --git a/src/hb-ot-os2-table.hh b/src/hb-ot-os2-table.hh
index e06ed57..67890f7 100644
--- a/src/hb-ot-os2-table.hh
+++ b/src/hb-ot-os2-table.hh
@@ -112,10 +112,11 @@
     OBLIQUE		= 1u<<9
   };
 
-  inline bool is_italic (void) const  { return fsSelection & ITALIC; }
-  inline bool is_oblique (void) const { return fsSelection & OBLIQUE; }
+  inline bool is_italic (void) const       { return fsSelection & ITALIC; }
+  inline bool is_oblique (void) const      { return fsSelection & OBLIQUE; }
+  inline bool is_typo_metrics (void) const { return fsSelection & USE_TYPO_METRICS; }
 
-  enum us_width_class_t {
+  enum width_class_t {
     FWIDTH_ULTRA_CONDENSED	= 1, /* 50% */
     FWIDTH_EXTRA_CONDENSED	= 2, /* 62.5% */
     FWIDTH_CONDENSED		= 3, /* 75% */