Move field-dependent code in ComputedStyleBase to Jinja macros.

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 48 matching lines @@
     // Affects how the interface to this field is generated.
     // TODO(sashab, meade): Remove this once TypedOM types are specified for
     // every property, since this value can be inferred from that.
     field_template: {
       valid_values: [
         // Field is stored as an enum and has a initial/getter/setter/resetter.
         "keyword",
         // Field is stored a packed boolean flag and has a initial/getter/setter/resetter.
         // TODO(shend): generalise this to "primitive"
         "flag",
+        // Field is stored as a bool, whose default value is false
+        // and can only be set to true. Has a initial/getter/setter.
+        "monotonic_flag"
       ],
     },
 
     // - field_type_path: "path/to/Type"
     // For properties that have generated field storage in ComputedStyle,
     // this optional argument will override the field's generated type with
     // an external one specified at the given path. The type must be defined
     // in a header file at that path, and have the same name as the file.
     // Currently, only enum types are supported, and the enum's only values
     // must be CamelCase values of the keywords of the property.
@@ skipping 3023 matching lines @@
     {
       name: "-webkit-transition-timing-function",
       alias_for: "transition-timing-function",
     },
     {
       name: "-webkit-user-select",
       alias_for: "user-select",
     },
   ],
 }