Improve CSS Style matching spec compliance

Source/platform/fonts/FontTraits.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 14 matching lines @@
  */
 
 #ifndef FontTraits_h
 #define FontTraits_h
 
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 enum FontWeight {
-    FontWeight100,
-    FontWeight200,
-    FontWeight300,
-    FontWeight400,
-    FontWeight500,
-    FontWeight600,
-    FontWeight700,
-    FontWeight800,
-    FontWeight900,
+    FontWeight100 = 0,
+    FontWeight200 = 1,
+    FontWeight300 = 2,
+    FontWeight400 = 3,
+    FontWeight500 = 4,
+    FontWeight600 = 5,
+    FontWeight700 = 6,
+    FontWeight800 = 7,
+    FontWeight900 = 8,
     FontWeightNormal = FontWeight400,
     FontWeightBold = FontWeight700
 };
 
 // Numeric values matching OS/2 & Windows Metrics usWidthClass table.
 // https://www.microsoft.com/typography/otspec/os2.htm
 enum FontStretch {
     FontStretchUltraCondensed = 1,
     FontStretchExtraCondensed = 2,
     FontStretchCondensed = 3,
     FontStretchSemiCondensed = 4,
     FontStretchNormal = 5,
     FontStretchSemiExpanded = 6,
     FontStretchExpanded = 7,
     FontStretchExtraExpanded = 8,
     FontStretchUltraExpanded = 9
 };
 
 enum FontStyle {
     FontStyleNormal = 0,
-    FontStyleItalic = 1
+    FontStyleOblique = 1,
+    FontStyleItalic = 2
 };
 
 enum FontVariant {
     FontVariantNormal = 0,
     FontVariantSmallCaps = 1
 };
 
 typedef unsigned FontTraitsBitfield;
 
 struct FontTraits {
     FontTraits(FontStyle style, FontVariant variant, FontWeight weight, FontStretch stretch)
     {
         m_traits.m_style = style;
+        // TODO(drott): crbug.com/516673 Variant is not relevant for font selection,
+        // should be removed here.
         m_traits.m_variant = variant;
         m_traits.m_weight = weight;
         m_traits.m_stretch = stretch;
         m_traits.m_filler = 0;
-        ASSERT(!(m_bitfield >> 10));
+        ASSERT(!(m_bitfield >> 11));
     }
     FontTraits(FontTraitsBitfield bitfield)
         : m_bitfield(bitfield)
     {
         ASSERT(!m_traits.m_filler);
-        ASSERT(!(m_bitfield >> 10));
+        ASSERT(!(m_bitfield >> 11));
     }
     FontStyle style() const { return static_cast<FontStyle>(m_traits.m_style); }
     FontVariant variant() const { return static_cast<FontVariant>(m_traits.m_variant); }
     FontWeight weight() const { return static_cast<FontWeight>(m_traits.m_weight); }
     FontStretch stretch() const { return static_cast<FontStretch>(m_traits.m_stretch); }
     FontTraitsBitfield bitfield() const { return m_bitfield; }
 
     union {
         struct {
-            unsigned m_style : 1;
+            unsigned m_style : 2;
             unsigned m_variant : 1;
             unsigned m_weight : 4;
             unsigned m_stretch : 4;
-            unsigned m_filler : 22;
+            unsigned m_filler : 21;
         } m_traits;
         FontTraitsBitfield m_bitfield;
     };
 };
 
 } // namespace blink
 #endif // FontTraits_h