After the patch in Bug 52920, we have the following hand-built RenderObjects for <input type=range> * RenderSliderThumb in SliderThumbElement.cpp horizontal/vertical switching and thumb positioning * RenderSliderContainer in SliderThumbElement.cpp horizontal/vertical switching and height adjustment * RenderSlider basePosition(), computePreferredLogicalWidths(), inDragMode(), etc. We'd like to reduce them.
Bug 240794 removed RenderSliderThumb