GraphicsContext::createImageBuffer should not create ImageBuffers that are backed by display lists

The calling code which creates ImageBuffers is never agnostic to whether the created buffer is backed by a display list or not.

If the calling code intends to use the display list as display list, it needs to access the list. This is done by creating DisplayList::Recorder explicitly.

Even if the target GraphicsContext would be a DisplayList::Recorder, creating a new image buffer as a display list and drawing that to the target would end up resulting a bitmap drawn to the target.