Remove the old multicol implementation.

Source/core/paint/ViewPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/ViewPainter.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/BlockPainter.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 #include "core/paint/PaintInfo.h"
 #include "platform/RuntimeEnabledFeatures.h"
 
 namespace blink {
 
 void ViewPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     // If we ever require layout but receive a paint anyway, something has gone horribly wrong.
     ASSERT(!m_layoutView.needsLayout());
     // LayoutViews should never be called to paint with an offset not on device pixels.
     ASSERT(LayoutPoint(IntPoint(paintOffset.x(), paintOffset.y())) == paintOffset);
 
-    // This avoids painting garbage between columns if there is a column gap.
-    // This is legacy WebKit behavior and doesn't work with slimmingpaint. We can remove it once region-based columns are launched.
-    if (!RuntimeEnabledFeatures::regionBasedColumnsEnabled() && m_layoutView.frameView() && m_layoutView.style()->isOverflowPaged()) {
-        ASSERT(!RuntimeEnabledFeatures::slimmingPaintEnabled());
-        LayoutRect paintRect(paintInfo.rect);
-        paintInfo.context->fillRect(paintRect, m_layoutView.frameView()->baseBackgroundColor());
-    }
-
     m_layoutView.paintObject(paintInfo, paintOffset);
     BlockPainter(m_layoutView).paintOverflowControlsIfNeeded(paintInfo, paintOffset);
 }
 
 static inline bool layoutObjectObscuresBackground(LayoutBox* rootBox)
 {
     ASSERT(rootBox);
     const ComputedStyle& style = rootBox->styleRef();
     if (style.visibility() != VISIBLE
         || style.opacity() != 1
@@ skipping 50 matching lines @@
 {
     ASSERT(rootBox);
     // CSS Boxes always fill the viewport background (see paintRootBoxFillLayers)
     if (!rootBox->isSVG())
         return true;
 
     return rootBox->frameRect().contains(m_layoutView.frameRect());
 }
 
 } // namespace blink