Moved GL enums from GraphicsContext3D to a more generic location.

Source/platform/graphics/ImageBuffer.cpp

Index: Source/platform/graphics/ImageBuffer.cpp
diff --git a/Source/platform/graphics/ImageBuffer.cpp b/Source/platform/graphics/ImageBuffer.cpp
index 4151a1c0808f99bff1d4c270ce02d62ca99ea9f7..5597392b716066315d7d3309f4517140e9e96a13 100644
--- a/Source/platform/graphics/ImageBuffer.cpp
+++ b/Source/platform/graphics/ImageBuffer.cpp
@@ -276,7 +276,7 @@ bool ImageBuffer::copyToPlatformTexture(GraphicsContext3D& context, Platform3DOb
     // The canvas is stored in an inverted position, so the flip semantics are reversed.
     context.pixelStorei(Extensions3D::UNPACK_FLIP_Y_CHROMIUM, !flipY);
 
-    extensions->copyTextureCHROMIUM(GraphicsContext3D::TEXTURE_2D, sourceTexture, texture, level, internalFormat, destType);
+    extensions->copyTextureCHROMIUM(GL_TEXTURE_2D, sourceTexture, texture, level, internalFormat, destType);
 
     context.pixelStorei(Extensions3D::UNPACK_FLIP_Y_CHROMIUM, false);
     context.pixelStorei(Extensions3D::UNPACK_UNPREMULTIPLY_ALPHA_CHROMIUM, false);
@@ -308,8 +308,8 @@ bool ImageBuffer::copyRenderingResultsFromDrawingBuffer(DrawingBuffer* drawingBu
     if (!context3D || !tex)
         return false;
 
-    return drawingBuffer->copyToPlatformTexture(*(context3D.get()), tex, GraphicsContext3D::RGBA,
-        GraphicsContext3D::UNSIGNED_BYTE, 0, true, false);
+    return drawingBuffer->copyToPlatformTexture(*(context3D.get()), tex, GL_RGBA,
+        GL_UNSIGNED_BYTE, 0, true, false);
 }
 
 void ImageBuffer::draw(GraphicsContext* context, const FloatRect& destRect, const FloatRect& srcRect,