Implement support for the 'transform-box' property

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

Index: third_party/WebKit/Source/core/css/CSSProperties.json5
diff --git a/third_party/WebKit/Source/core/css/CSSProperties.json5 b/third_party/WebKit/Source/core/css/CSSProperties.json5
index 96bfa49c5fd7604c7b9512f8c3a4b3f63233a8e6..795b2213184fe9addab098ec042655da117f8b96 100644
--- a/third_party/WebKit/Source/core/css/CSSProperties.json5
+++ b/third_party/WebKit/Source/core/css/CSSProperties.json5
@@ -1923,6 +1923,13 @@
       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"],