Add test for typeface style round trip.

include/core/SkFontStyle.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkFontStyle_DEFINED
 #define SkFontStyle_DEFINED
 
 #include "SkTypes.h"
 
 class SK_API SkFontStyle {
 public:
     enum Weight {
-        kThin_Weight        = 100,
-        kExtraLight_Weight  = 200,
-        kLight_Weight       = 300,
-        kNormal_Weight      = 400,
-        kMedium_Weight      = 500,
-        kSemiBold_Weight    = 600,
-        kBold_Weight        = 700,
-        kExtraBold_Weight   = 800,
-        kBlack_Weight       = 900
+        kInvisible_Weight   =    0,
+        kThin_Weight        =  100,
+        kExtraLight_Weight  =  200,
+        kLight_Weight       =  300,
+        kNormal_Weight      =  400,
+        kMedium_Weight      =  500,
+        kSemiBold_Weight    =  600,
+        kBold_Weight        =  700,
+        kExtraBold_Weight   =  800,
+        kBlack_Weight       =  900,
+        kExtraBlack_Weight  = 1000
     };
 
     enum Width {
         kUltraCondensed_Width   = 1,
         kExtraCondensed_Width   = 2,
         kCondensed_Width        = 3,
         kSemiCondensed_Width    = 4,
         kNormal_Width           = 5,
         kSemiExpanded_Width     = 6,
         kExpanded_Width         = 7,
@@ skipping 25 matching lines @@
         struct {
             uint16_t fWeight;   // 100 .. 900
             uint8_t  fWidth;    // 1 .. 9
             uint8_t  fSlant;    // 0 .. 2
         } fR;
         uint32_t    fU32;
     } fUnion;
 };
 
 #endif