Implement support for the 'transform-box' property

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 1905 matching lines @@
       type_name: "TouchAction",
     },
     {
       name: "transform",
       converter: "convertTransformOperations",
       interpolable: true,
       keywords: ["none"],
       typedom_types: ["Transform"],
     },
     {
+      name: "transform-box",
+      field_template: "keyword",
+      keywords: ["border-box", "fill-box", "view-box"],
+      initial_keyword: "border-box",

[pdr., 2017/04/04 22:47:13]

Because I took forever to review this, something changed in the format. I think
this now needs to be default_value.

[fs, 2017/04/05 08:48:17]

Will fix.

+      runtime_flag: "CSSTransformBox",
+    },
+    {
       name: "transform-origin",
       api_class: true,
       api_methods: ["parseSingleValue"],
       converter: "convertTransformOrigin",
       interpolable: true,
     },
     {
       name: "transform-style",
       name_for_methods: "TransformStyle3D",
     },
@@ skipping 1229 matching lines @@
     {
       name: "-webkit-transition-timing-function",
       alias_for: "transition-timing-function",
     },
     {
       name: "-webkit-user-select",
       alias_for: "user-select",
     },
   ],
 }