Remove the old multicol implementation.

Source/core/paint/BoxPainter.cpp

Index: Source/core/paint/BoxPainter.cpp
diff --git a/Source/core/paint/BoxPainter.cpp b/Source/core/paint/BoxPainter.cpp
index 03f2e91244e8791fe91554d4f865225e5f48309a..dca38860090b7bc3d4d8fdd52d8134b942862e78 100644
--- a/Source/core/paint/BoxPainter.cpp
+++ b/Source/core/paint/BoxPainter.cpp
@@ -74,7 +74,7 @@ LayoutRect BoxPainter::boundsForDrawingRecorder(const LayoutPoint& paintOffset)
 LayoutRect BoxPainter::rootBackgroundRect()
 {
     LayoutView* layoutView = m_layoutBox.view();
-    LayoutRect result = layoutView->backgroundRect(&m_layoutBox);
+    LayoutRect result(layoutView->unscaledDocumentRect());

[dsinclair, 2015/06/03 13:52:58]

This change seems unrelated?

[mstensho (USE GERRIT), 2015/06/03 13:56:21]

I killed LayoutView::backgroundRect(), because it no longer did anything unique,
because of the removal of the old multicol code. Should I put it back?

[mstensho (USE GERRIT), 2015/06/03 14:05:52]

Done.

     // In root-layer-scrolls mode, root background is painted in coordinates of the
     // root scrolling contents layer, so don't need scroll offset adjustment.
     if (layoutView->hasOverflowClip() && !layoutView->frame()->settings()->rootLayerScrolls())