Rename ExceptionCode constants to use the names in the spec (2/3)

Source/core/html/canvas/CanvasGradient.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  *
  * 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 36 matching lines @@
 
 void CanvasGradient::addColorStop(float value, const String& color, ExceptionCode& ec)
 {
     if (!(value >= 0 && value <= 1.0f)) {
         ec = IndexSizeError;
         return;
     }
 
     RGBA32 rgba = 0;
     if (!parseColorOrCurrentColor(rgba, color, 0 /*canvas*/)) {
-        ec = SYNTAX_ERR;
+        ec = SyntaxError;
         return;
     }
 
     m_gradient->addColorStop(value, Color(rgba));
 }
 
 } // namespace