Don't apply container flip when computing offset to transformed ancestor.

third_party/WebKit/Source/core/paint/PaintLayer.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index 6185791da27c422789c8af3b73af3261dacdf97c..886064cf0326d267fe9bcd29f5ecf6fb61fa76fe 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -904,8 +904,7 @@ PaintLayer* PaintLayer::enclosingTransformedAncestor() const
 LayoutPoint PaintLayer::computeOffsetFromTransformedAncestor() const
 {
     TransformState transformState(TransformState::ApplyTransformDirection, FloatPoint());
-    // FIXME: add a test that checks flipped writing mode and ApplyContainerFlip are correct.
-    layoutObject()->mapLocalToAncestor(transformAncestor() ? transformAncestor()->layoutObject() : nullptr, transformState, ApplyContainerFlip);
+    layoutObject()->mapLocalToAncestor(transformAncestor() ? transformAncestor()->layoutObject() : nullptr, transformState, 0);
     transformState.flatten();
     return LayoutPoint(transformState.lastPlanarPoint());
 }