Layout support for new circle shape syntax

Source/core/css/BasicShapeFunctions.cpp

 /*
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 303 matching lines @@
     }
     default:
         break;
     }
 
     if (basicShapeValue->layoutBox())
         basicShape->setLayoutBox(LayoutBox(*basicShapeValue->layoutBox()));
 
     return basicShape.release();
 }
+
+float floatValueForCenterCoordinate(const BasicShapeCenterCoordinate& center, float boxDimension)
+{
+    float offset = floatValueForLength(center.length(), boxDimension);
+    switch (center.keyword()) {
+    case BasicShapeCenterCoordinate::None:
+        return offset;
+    case BasicShapeCenterCoordinate::Top:
+    case BasicShapeCenterCoordinate::Left:
+        return offset;
+    case BasicShapeCenterCoordinate::Bottom:
+    case BasicShapeCenterCoordinate::Right:
+        return boxDimension - offset;
+    }
+
+    ASSERT_NOT_REACHED();
+    return 0;
 }
+
+}