Handle exclusive end offsets when translating from flow thread coordinates.

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

Index: third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.h
diff --git a/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.h b/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.h
index f49b93e6ddfd7331e2181157cadb94242804cc74..343c8df31e7f31fcfe940378e79304fa4406e281 100644
--- a/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.h
+++ b/third_party/WebKit/Source/core/layout/MultiColumnFragmentainerGroup.h
@@ -62,7 +62,7 @@ public:
     void resetColumnHeight();
     bool recalculateColumnHeight(LayoutMultiColumnSet&);
 
-    LayoutSize flowThreadTranslationAtOffset(LayoutUnit, CoordinateSpaceConversion) const;
+    LayoutSize flowThreadTranslationAtOffset(LayoutUnit, LayoutBox::PageBoundaryRule, CoordinateSpaceConversion) const;
     LayoutUnit columnLogicalTopForOffset(LayoutUnit offsetInFlowThread) const;
     LayoutPoint visualPointToFlowThreadPoint(const LayoutPoint& visualPoint) const;
     LayoutRect fragmentsBoundingBox(const LayoutRect& boundingBoxInFlowThread) const;
@@ -78,13 +78,10 @@ public:
 
     LayoutRect calculateOverflow() const;
 
-    enum ColumnIndexCalculationMode {
-        ClampToExistingColumns, // Stay within the range of already existing columns.
-        AssumeNewColumns // Allow column indices outside the range of already existing columns.
-    };
-    unsigned columnIndexAtOffset(LayoutUnit offsetInFlowThread, ColumnIndexCalculationMode = ClampToExistingColumns) const;
+    unsigned columnIndexAtOffset(LayoutUnit offsetInFlowThread, LayoutBox::PageBoundaryRule) const;
 
     // The "CSS actual" value of column-count. This includes overflowing columns, if any.
+    // Returns 1 or greater, never 0.
     unsigned actualColumnCount() const;
 
 private: