Generate getters/setters for tab-size.

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 1954 matching lines @@
       ]
     },
     {
       name: "tab-size",
       api_class: true,
       api_methods: ["parseSingleValue"],
       converter: "ConvertLengthOrTabSpaces",
       inherited: true,
       getter: "GetTabSize",
       field_type_path: "platform/text/TabSize",
-      field_template: "storage_only",
+      field_template: "external",
       default_value: "TabSize(8)",
       field_group: "rare-inherited",
     },
     {
       name: "text-align",
       custom_value: true,
       independent: false,
       inherited: true,
       default_value: "start",
       field_template: "keyword",
@@ skipping 1506 matching lines @@
     {
       name: "-webkit-transition-timing-function",
       alias_for: "transition-timing-function",
     },
     {
       name: "-webkit-user-select",
       alias_for: "user-select",
     },
   ],
 }