Implement support for the 'transform-box' property

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

 {
   // The mode argument is used to limit the keyword to be used only for certain
   // CSSParserModes. Values that have the prefix -internal- are only allowed by
   // CSSParserModes listed in allowInternalPropertyAndValue()
 
   parameters: {
     mode: {},
   },
 
   //
@@ skipping 734 matching lines @@
     "running",
     "paused",
 
     //
     // transform-style
     //
     "flat",
     "preserve-3d",
 
     //
+    // transform-box
+    //
+    // border-box
+    "fill-box",
+    "view-box",
+
+    //
     // transition-timing-function
     // animation-timing-function
     //
     "ease",
     "linear",
     "ease-in",
     "ease-out",
     "ease-in-out",
     "step-start",
     "step-middle",
@@ skipping 361 matching lines @@
     // shape
     // rect
     // round
 
     // color-gamut
     // srgb
     "p3",
     "rec2020",
   ],
 }