Translate the clip rect correctly when iterating over fragmentainers.

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

Index: third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
diff --git a/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp b/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
index e7c13ea161b85452edd09e09699de83cc08d91b5..884c70a7fa2b6e93a3446fda02d3cb8518a3c14c 100644
--- a/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
+++ b/third_party/WebKit/Source/core/layout/FragmentainerIterator.cpp
@@ -99,10 +99,14 @@ bool FragmentainerIterator::setFragmentainersOfInterest()
     // might not have to walk the entire fragmentainer group.
     group.columnIntervalForBlockRangeInFlowThread(m_logicalTopInFlowThread, m_logicalBottomInFlowThread, m_currentFragmentainerIndex, m_endFragmentainerIndex);
 
-    // Now intersect with the fragmentainers that actually intersect with the clip rect, to narrow
-    // it down even further.
+    // Now intersect with the fragmentainers that actually intersect with the visual clip rect, to
+    // narrow it down even further. The clip rect needs to be relative to the current fragmentainer
+    // group.
+    LayoutRect clipRect = m_clipRectInMulticolContainer;
+    LayoutSize offset = group.flowThreadTranslationAtOffset(group.logicalTopInFlowThread(), CoordinateSpaceConversion::Visual);
+    clipRect.move(-offset);
     unsigned firstFragmentainerInClipRect, lastFragmentainerInClipRect;
-    group.columnIntervalForVisualRect(m_clipRectInMulticolContainer, firstFragmentainerInClipRect, lastFragmentainerInClipRect);
+    group.columnIntervalForVisualRect(clipRect, firstFragmentainerInClipRect, lastFragmentainerInClipRect);
     // If the two fragmentainer intervals are disjoint, there's nothing of interest in this
     // fragmentainer group.
     if (firstFragmentainerInClipRect > m_endFragmentainerIndex || lastFragmentainerInClipRect < m_currentFragmentainerIndex)