Make TextUnderlinePosition an enum class.

third_party/WebKit/Source/core/style/ComputedStyle.h

Index: third_party/WebKit/Source/core/style/ComputedStyle.h
diff --git a/third_party/WebKit/Source/core/style/ComputedStyle.h b/third_party/WebKit/Source/core/style/ComputedStyle.h
index aec4bd46d6b9d3bdc12a756d13a7e73a06934c55..5ec0fab502ac330ed126adf43ab81d8e3de6d33c 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyle.h
+++ b/third_party/WebKit/Source/core/style/ComputedStyle.h
@@ -1475,14 +1475,15 @@ class CORE_EXPORT ComputedStyle : public ComputedStyleBase<ComputedStyle>,
 
   // text-underline-position
   static TextUnderlinePosition InitialTextUnderlinePosition() {
-    return kTextUnderlinePositionAuto;
+    return TextUnderlinePosition::kAuto;
   }
   TextUnderlinePosition GetTextUnderlinePosition() const {
     return static_cast<TextUnderlinePosition>(
         rare_inherited_data_->text_underline_position_);
   }
   void SetTextUnderlinePosition(TextUnderlinePosition v) {
-    SET_VAR(rare_inherited_data_, text_underline_position_, v);
+    SET_VAR(rare_inherited_data_, text_underline_position_,
+            static_cast<unsigned>(v));
   }
 
   // text-decoration-skip