Support subpixel layout for borders.

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 584 matching lines @@
       initial: "initialBorderRadius",
       interpolable: true,
     },
     {
       name: "border-bottom-style",
       initial: "initialBorderStyle",
       type_name: "EBorderStyle",
     },
     {
       name: "border-bottom-width",
-      converter: "convertLineWidth<unsigned>",
+      converter: "convertLineWidth<float>",
       initial: "initialBorderWidth",
       interpolable: true,
     },
     {
       name: "border-collapse",
       independent: true,
       inherited: true,
       initial_keyword: "separate",
       keyword_only: true,
       keywords: ["separate", "collapse"],
@@ skipping 30 matching lines @@
       custom_all: true,
       interpolable: true,
     },
     {
       name: "border-left-style",
       initial: "initialBorderStyle",
       type_name: "EBorderStyle",
     },
     {
       name: "border-left-width",
-      converter: "convertLineWidth<unsigned>",
+      converter: "convertLineWidth<float>",
       initial: "initialBorderWidth",
       interpolable: true,
     },
     {
       name: "border-right-color",
       custom_all: true,
       interpolable: true,
     },
     {
       name: "border-right-style",
       initial: "initialBorderStyle",
       type_name: "EBorderStyle",
     },
     {
       name: "border-right-width",
-      converter: "convertLineWidth<unsigned>",
+      converter: "convertLineWidth<float>",
       initial: "initialBorderWidth",
       interpolable: true,
     },
     {
       name: "border-top-color",
       custom_all: true,
       interpolable: true,
     },
     {
       name: "border-top-left-radius",
       api_class: "CSSPropertyAPIBorderRadius",
       converter: "convertRadius",
       initial: "initialBorderRadius",
       interpolable: true,
     },
     {
       name: "border-top-right-radius",
       api_class: "CSSPropertyAPIBorderRadius",
       converter: "convertRadius",
       initial: "initialBorderRadius",
       interpolable: true,
     },
     {
       name: "border-top-style",
       initial: "initialBorderStyle",
       type_name: "EBorderStyle",
     },
     {
       name: "border-top-width",
-      converter: "convertLineWidth<unsigned>",
+      converter: "convertLineWidth<float>",
       initial: "initialBorderWidth",
       interpolable: true,
       keywords: ["thin", "medium", "thick"],
       supports_percentage: true,
       typedom_types: ["Length"],
     },
     {
       name: "bottom",
       converter: "convertLengthOrAuto",
       initial: "initialOffset",
@@ skipping 2091 matching lines @@
     {
       name: "-webkit-transition-timing-function",
       alias_for: "transition-timing-function",
     },
     {
       name: "-webkit-user-select",
       alias_for: "user-select",
     },
   ],
 }