[New Multicolumn] Margins incorrectly accounted for before forced breaks.

Source/core/rendering/RenderBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1736 matching lines @@
 LayoutUnit RenderBlockFlow::applyAfterBreak(RenderBox& child, LayoutUnit logicalOffset, MarginInfo& marginInfo)
 {
     // FIXME: Add page break checking here when we support printing.
     RenderFlowThread* flowThread = flowThreadContainingBlock();
     bool isInsideMulticolFlowThread = flowThread;
     bool checkColumnBreaks = isInsideMulticolFlowThread || view()->layoutState()->isPaginatingColumns();
     bool checkPageBreaks = !checkColumnBreaks && view()->layoutState()->pageLogicalHeight(); // FIXME: Once columns can print we have to check this.
     bool checkAfterAlways = (checkColumnBreaks && child.style()->columnBreakAfter() == PBALWAYS)
         || (checkPageBreaks && child.style()->pageBreakAfter() == PBALWAYS);
     if (checkAfterAlways && inNormalFlow(&child)) {
-        LayoutUnit marginOffset = marginInfo.canCollapseWithMarginBefore() ? LayoutUnit() : marginInfo.margin();
-
         // So our margin doesn't participate in the next collapsing steps.
         marginInfo.clearMargin();
 
         if (checkColumnBreaks) {
             if (isInsideMulticolFlowThread) {
                 LayoutUnit offsetBreakAdjustment = 0;
-                if (flowThread->addForcedRegionBreak(offsetFromLogicalTopOfFirstPage() + logicalOffset + marginOffset, &child, false, &offsetBreakAdjustment))
-                    return logicalOffset + marginOffset + offsetBreakAdjustment;
+                if (flowThread->addForcedRegionBreak(offsetFromLogicalTopOfFirstPage() + logicalOffset, &child, false, &offsetBreakAdjustment))
+                    return logicalOffset + offsetBreakAdjustment;
             } else {
                 view()->layoutState()->addForcedColumnBreak(child, logicalOffset);
             }
         }
         return nextPageLogicalTop(logicalOffset, IncludePageBoundary);
     }
     return logicalOffset;
 }
 
 void RenderBlockFlow::addOverflowFromFloats()
@@ skipping 1344 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (size().height() < visibleHeight)
         top += (visibleHeight - size().height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink