Handle auto-positioned out-of-flow objects inside multicol containers correctly.

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

Index: third_party/WebKit/Source/core/layout/LayoutFlowThread.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlowThread.cpp b/third_party/WebKit/Source/core/layout/LayoutFlowThread.cpp
index 5eae393e2aa636d4e15d5605d726220a4a2fb9e6..3002b95552d8e3b2389fee4d20dee9fd8c2df18d 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlowThread.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFlowThread.cpp
@@ -187,6 +187,24 @@ LayoutRect LayoutFlowThread::fragmentsBoundingBox(const LayoutRect& layerBoundin
     return result;
 }
 
+void LayoutFlowThread::flowThreadToContainingCoordinateSpace(LayoutUnit& blockPosition, LayoutUnit& inlinePosition) const
+{
+    LayoutPoint position(inlinePosition, blockPosition);
+    // First we have to make |position| physical, because that's what offsetLeft() expects and returns.
+    if (!isHorizontalWritingMode())
+        position = position.transposedPoint();
+    position = flipForWritingMode(position);
+
+    position.move(columnOffset(position));
+
+    // Make |position| logical again, and read out the values.
+    position = flipForWritingMode(position);
+    if (!isHorizontalWritingMode())
+        position = position.transposedPoint();
+    blockPosition = position.y();
+    inlinePosition = position.x();
+}
+
 void LayoutFlowThread::MultiColumnSetSearchAdapter::collectIfNeeded(const MultiColumnSetInterval& interval)
 {
     if (m_result)