Changed GL enums from GraphicsContext3D to standard versions (Take 2)

Source/platform/graphics/GraphicsTypes3D.h

Index: Source/platform/graphics/GraphicsTypes3D.h
diff --git a/Source/platform/graphics/GraphicsTypes3D.h b/Source/platform/graphics/GraphicsTypes3D.h
index a48f45994c51724bbda3ab9586844c6e402e713c..a4ed898127b712e3796f6744efe074b489b019c5 100644
--- a/Source/platform/graphics/GraphicsTypes3D.h
+++ b/Source/platform/graphics/GraphicsTypes3D.h
@@ -29,8 +29,8 @@
 #include "wtf/Forward.h"
 #include <stdint.h>
 
-// GC3D types match the corresponding GL types as defined in OpenGL ES 2.0
-// header file gl2.h from khronos.org.
+// GC3D types and enums match the corresponding GL types and enums as defined
+// in OpenGL ES 2.0 header file gl2.h from khronos.org.
 typedef unsigned GC3Denum;
 typedef unsigned char GC3Dboolean;
 typedef unsigned GC3Dbitfield;
@@ -50,4 +50,12 @@ typedef char GC3Dchar;
 
 typedef GC3Duint Platform3DObject;
 
+// WebGL-specific enums
+const GC3Denum GC3D_DEPTH_STENCIL_ATTACHMENT_WEBGL = 0x821A;
+const GC3Denum GC3D_UNPACK_FLIP_Y_WEBGL = 0x9240;
+const GC3Denum GC3D_UNPACK_PREMULTIPLY_ALPHA_WEBGL = 0x9241;
+const GC3Denum GC3D_CONTEXT_LOST_WEBGL = 0x9242;
+const GC3Denum GC3D_UNPACK_COLORSPACE_CONVERSION_WEBGL = 0x9243;
+const GC3Denum GC3D_BROWSER_DEFAULT_WEBGL = 0x9244;
+
 #endif