[SVGDom] Parse style attributes

experimental/svg/model/SkSVGAttribute.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSVGAttribute_DEFINED
 #define SkSVGAttribute_DEFINED
 
 #include "SkColor.h"
 #include "SkTLazy.h"
 
 enum class SkSVGAttribute {
-    d,
-    fill,
-    stroke,
-    transform,
+    kD,
+    kFill,
+    kStroke,
+    kTransform,
+
+    kUnknown,
 };
 
 class SkSVGRenderContext;
 
 class SkSVGPresentationAttributes {
 public:
     SkSVGPresentationAttributes();
 
     void setFill(SkColor);
     void setStroke(SkColor);
 
     void applyTo(SkTCopyOnFirstWrite<SkSVGRenderContext>&) const;
 
 private:
     // Color only for now.
     SkColor fFill;
     SkColor fStroke;
 
     unsigned fFillIsSet   : 1;
     unsigned fStrokeIsSet : 1;
 };
 
 #endif // SkSVGAttribute_DEFINED