*** NOT FOR LANDING *** mapLocalToContainer and offsetFromContainer cleanup.

Source/core/layout/LayoutMultiColumnFlowThread.cpp

Index: Source/core/layout/LayoutMultiColumnFlowThread.cpp
diff --git a/Source/core/layout/LayoutMultiColumnFlowThread.cpp b/Source/core/layout/LayoutMultiColumnFlowThread.cpp
index 423cde52e9e5ac21432e0831966b1b1ad43c20b4..1734b7965b7b9bb7f7779906400e11f69984de78 100644
--- a/Source/core/layout/LayoutMultiColumnFlowThread.cpp
+++ b/Source/core/layout/LayoutMultiColumnFlowThread.cpp
@@ -28,6 +28,7 @@
 
 #include "core/layout/LayoutMultiColumnSet.h"
 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
+#include "platform/geometry/TransformState.h"
 
 namespace blink {
 
@@ -851,6 +852,15 @@ void LayoutMultiColumnFlowThread::layout()
     m_lastSetWorkedOn = nullptr;
 }
 
+void LayoutMultiColumnFlowThread::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
+{
+    LayoutFlowThread::mapAbsoluteToLocalPoint(mode, transformState);
+
+    // Descending into a multicol flow thread. Convert to the local coordinate space, i.e. flow thread coordinates.
+    LayoutPoint visualPoint = LayoutPoint(transformState.mappedPoint());
+    transformState.move(visualPoint - visualPointToFlowThreadPoint(visualPoint));
+}
+
 void LayoutMultiColumnFlowThread::setPageBreak(LayoutUnit offset, LayoutUnit spaceShortage)
 {
     // Only positive values are interesting (and allowed) here. Zero space shortage may be reported