Make EFlexWrap an enum class.

third_party/WebKit/Source/core/css/CSSProperties.json5

 {
 // This file specifies all the CSS properties we support and the necessary
 // information for our code generation. The various supported arguments
 // are described below with example usage
 
   parameters: {
     // - alias_for: "other-property"
     // Properties specifying alias_for should be virtually identical to the
     // properties they alias. Minor parsing differences are allowed as long as
     // the CSSValues created are of the same format of the aliased property.
@@ skipping 1226 matching lines @@
       interpolable: true,
       type_name: "float",
       field_template: "storage_only",
       default_value: "1.0f",
       field_group: "rare-non-inherited->flexible-box",
     },
     {
       name: "flex-wrap",
       type_name: "EFlexWrap",
       field_template: "storage_only",
-      default_value: "kFlexNoWrap",
+      default_value: "EFlexWrap::kNowrap",
       field_size: 2,
       field_group: "rare-non-inherited->flexible-box",
     },
     {
       name: "float",
       default_value: "none",
       field_template: "keyword",
       keywords: ["none", "left", "right"],
       name_for_methods: "Floating",
       type_name: "EFloat",
@@ skipping 2835 matching lines @@
     {
       name: "-webkit-transition-timing-function",
       alias_for: "transition-timing-function",
     },
     {
       name: "-webkit-user-select",
       alias_for: "user-select",
     },
   ],
 }