Make column snapping optional when translating to flow thread coordinates.

third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp

 /*
  * Copyright (C) 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 456 matching lines @@
     logicalHeight += group.logicalHeight();
   computedValues.m_extent = logicalHeight;
   computedValues.m_position = logicalTop;
 }
 
 PositionWithAffinity LayoutMultiColumnSet::positionForPoint(
     const LayoutPoint& point) {
   // Convert the visual point to a flow thread point.
   const MultiColumnFragmentainerGroup& row =
       fragmentainerGroupAtVisualPoint(point);
-  LayoutPoint flowThreadPoint =
-      row.visualPointToFlowThreadPoint(point + row.offsetFromColumnSet());
+  LayoutPoint flowThreadPoint = row.visualPointToFlowThreadPoint(
+      point + row.offsetFromColumnSet(),
+      MultiColumnFragmentainerGroup::SnapToColumn);
   // Then drill into the flow thread, where we'll find the actual content.
   return flowThread()->positionForPoint(flowThreadPoint);
 }
 
 LayoutUnit LayoutMultiColumnSet::columnGap() const {
   LayoutBlockFlow* parentBlock = multiColumnBlockFlow();
 
   if (parentBlock->style()->hasNormalColumnGap()) {
     // "1em" is recommended as the normal gap setting. Matches <p> margins.
     return LayoutUnit(
@@ skipping 137 matching lines @@
   // Now add in column rule bounds, if present.
   Vector<LayoutRect> columnRuleBounds;
   if (computeColumnRuleBounds(LayoutPoint(), columnRuleBounds)) {
     for (auto& bound : columnRuleBounds)
       blockFlowBounds.unite(bound);
   }
   return blockFlowBounds;
 }
 
 }  // namespace blink