Add keyword_subset field template and generate text-decoration-line.

third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h

Index: third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h
diff --git a/third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h b/third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h
index bffbfbd1915d417846da30164a0fb3cdaf18d75c..b0d92650953122dc02af9ab8b70904f9e413102e 100644
--- a/third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h
+++ b/third_party/WebKit/Source/core/css/CSSPrimitiveValueMappings.h
@@ -657,27 +657,6 @@ inline ETableLayout CSSIdentifierValue::ConvertTo() const {
   return ETableLayout::kAuto;
 }
 
-template <>
-inline TextDecoration CSSIdentifierValue::ConvertTo() const {
-  switch (value_id_) {
-    case CSSValueNone:
-      return TextDecoration::kNone;
-    case CSSValueUnderline:
-      return TextDecoration::kUnderline;
-    case CSSValueOverline:
-      return TextDecoration::kOverline;
-    case CSSValueLineThrough:
-      return TextDecoration::kLineThrough;
-    case CSSValueBlink:
-      return TextDecoration::kBlink;
-    default:
-      break;
-  }
-
-  NOTREACHED();
-  return TextDecoration::kNone;
-}
-
 template <>
 inline TextDecorationSkip CSSIdentifierValue::ConvertTo() const {
   switch (value_id_) {