getClientRects() shouldn't clip against any ancestors.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/MultiColumnFragmentainerGroup.h"
 
 #include "core/layout/ColumnBalancer.h"
 #include "core/layout/FragmentationContext.h"
 #include "core/layout/LayoutMultiColumnSet.h"
 
@@ skipping 398 matching lines @@
   LayoutUnit logicalTop = logicalTopInFlowThreadAt(columnIndex);
   LayoutUnit portionLogicalHeight = logicalHeightInFlowThreadAt(columnIndex);
   if (m_columnSet.isHorizontalWritingMode())
     return LayoutRect(LayoutUnit(), logicalTop, m_columnSet.pageLogicalWidth(),
                       portionLogicalHeight);
   return LayoutRect(logicalTop, LayoutUnit(), portionLogicalHeight,
                     m_columnSet.pageLogicalWidth());
 }
 
 LayoutRect MultiColumnFragmentainerGroup::flowThreadPortionOverflowRectAt(
-    unsigned columnIndex) const {
+    unsigned columnIndex,
+    ClipRectAxesSelector axesSelector) const {
   // This function determines the portion of the flow thread that paints for the
   // column. Along the inline axis, columns are unclipped at outside edges
   // (i.e., the first and last column in the set), and they clip to half the
   // column gap along interior edges.
   //
   // In the block direction, we will not clip overflow out of the top of the
   // first column, or out of the bottom of the last column. This applies only to
   // the true first column and last column across all column sets.
   //
   // FIXME: Eventually we will know overflow on a per-column basis, but we can't
@@ skipping 17 matching lines @@
   // multicol container, in which case it should allow overflow. It will also
   // be clipped in the middle of adjacent column gaps. Care is taken here to
   // avoid rounding errors.
   LayoutRect overflowRect(LayoutRect::infiniteIntRect());
   LayoutUnit columnGap = m_columnSet.columnGap();
   if (m_columnSet.isHorizontalWritingMode()) {
     if (!isFirstColumnInMulticolContainer)
       overflowRect.shiftYEdgeTo(portionRect.y());
     if (!isLastColumnInMulticolContainer)
       overflowRect.shiftMaxYEdgeTo(portionRect.maxY());
-    if (!isLeftmostColumn)
-      overflowRect.shiftXEdgeTo(portionRect.x() - columnGap / 2);
-    if (!isRightmostColumn)
-      overflowRect.shiftMaxXEdgeTo(portionRect.maxX() + columnGap -
-                                   columnGap / 2);
+    if (axesSelector == BothAxes) {
+      if (!isLeftmostColumn)
+        overflowRect.shiftXEdgeTo(portionRect.x() - columnGap / 2);
+      if (!isRightmostColumn) {
+        overflowRect.shiftMaxXEdgeTo(portionRect.maxX() + columnGap -
+                                     columnGap / 2);
+      }
+    }
   } else {
     if (!isFirstColumnInMulticolContainer)
       overflowRect.shiftXEdgeTo(portionRect.x());
     if (!isLastColumnInMulticolContainer)
       overflowRect.shiftMaxXEdgeTo(portionRect.maxX());
-    if (!isLeftmostColumn)
-      overflowRect.shiftYEdgeTo(portionRect.y() - columnGap / 2);
-    if (!isRightmostColumn)
-      overflowRect.shiftMaxYEdgeTo(portionRect.maxY() + columnGap -
-                                   columnGap / 2);
+    if (axesSelector == BothAxes) {
+      if (!isLeftmostColumn)
+        overflowRect.shiftYEdgeTo(portionRect.y() - columnGap / 2);
+      if (!isRightmostColumn) {
+        overflowRect.shiftMaxYEdgeTo(portionRect.maxY() + columnGap -
+                                     columnGap / 2);
+      }
+    }
   }
   return overflowRect;
 }
 
 unsigned MultiColumnFragmentainerGroup::columnIndexAtOffset(
     LayoutUnit offsetInFlowThread,
     LayoutBox::PageBoundaryRule pageBoundaryRule) const {
   // Handle the offset being out of range.
   if (offsetInFlowThread < m_logicalTopInFlowThread)
     return 0;
@@ skipping 111 matching lines @@
 MultiColumnFragmentainerGroupList::addExtraGroup() {
   append(MultiColumnFragmentainerGroup(m_columnSet));
   return last();
 }
 
 void MultiColumnFragmentainerGroupList::deleteExtraGroups() {
   shrink(1);
 }
 
 }  // namespace blink