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

Source/core/layout/LayoutBoxModelObject.cpp

Index: Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/Source/core/layout/LayoutBoxModelObject.cpp b/Source/core/layout/LayoutBoxModelObject.cpp
index 0ede20bb48886f0899303a9591bdc06d1a5b0dd6..6beec09b373f5b2846152a59bf4fedb5b843eb08 100644
--- a/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/Source/core/layout/LayoutBoxModelObject.cpp
@@ -849,6 +849,14 @@ LayoutRect LayoutBoxModelObject::localCaretRectForEmptyElement(LayoutUnit width,
     return currentStyle.isHorizontalWritingMode() ? LayoutRect(x, y, caretWidth(), height) : LayoutRect(y, x, height, caretWidth());
 }
 
+LayoutSize LayoutBoxModelObject::offsetFromContainer(const LayoutObject* o) const
+{
+    LayoutSize offset;
+    if (isRelPositioned())
+        offset += offsetForInFlowPosition();
+    return offset + LayoutObject::offsetFromContainer(o);
+}
+
 void LayoutBoxModelObject::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
 {
     LayoutObject* o = container();
@@ -857,20 +865,7 @@ void LayoutBoxModelObject::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, Tra
 
     o->mapAbsoluteToLocalPoint(mode, transformState);
 
-    LayoutSize containerOffset = offsetFromContainer(o, LayoutPoint());
-
-    if (o->isLayoutFlowThread()) {
-        // Descending into a flow thread. Convert to the local coordinate space, i.e. flow thread coordinates.
-        const LayoutFlowThread* flowThread = toLayoutFlowThread(o);
-        LayoutPoint visualPoint = LayoutPoint(transformState.mappedPoint());
-        transformState.move(visualPoint - flowThread->visualPointToFlowThreadPoint(visualPoint));
-        // |containerOffset| is also in visual coordinates. Convert to flow thread coordinates.
-        // TODO(mstensho): Wouldn't it be better add a parameter to instruct offsetFromContainer()
-        // to return flowthread coordinates in the first place? We're effectively performing two
-        // conversions here, when in fact none is needed.
-        containerOffset = toLayoutSize(flowThread->visualPointToFlowThreadPoint(toLayoutPoint(containerOffset)));
-    }
-
+    LayoutSize containerOffset = offsetFromContainer(o);
     bool preserve3D = mode & UseTransforms && (o->style()->preserves3D() || style()->preserves3D());
     if (mode & UseTransforms && shouldUseTransformFromContainer(o)) {
         TransformationMatrix t;
@@ -901,8 +896,9 @@ const LayoutObject* LayoutBoxModelObject::pushMappingToContainer(const LayoutBox
         adjustmentForSkippedAncestor = -ancestorToStopAt->offsetFromAncestorContainer(container);
     }
 
-    bool offsetDependsOnPoint = false;
-    LayoutSize containerOffset = offsetFromContainer(container, LayoutPoint(), &offsetDependsOnPoint);
+    bool offsetDependsOnPoint = container->isBox() && (container->style()->isFlippedBlocksWritingMode() || container->isLayoutFlowThread());
+    LayoutSize containerOffset = offsetFromContainer(container);
+    containerOffset += container->columnOffset(toLayoutPoint(containerOffset));
 
     bool preserve3D = container->style()->preserves3D() || style()->preserves3D();
     if (shouldUseTransformFromContainer(container)) {