Avoid using floating point when not needed.

Source/core/layout/MultiColumnFragmentainerGroup.cpp

Index: Source/core/layout/MultiColumnFragmentainerGroup.cpp
diff --git a/Source/core/layout/MultiColumnFragmentainerGroup.cpp b/Source/core/layout/MultiColumnFragmentainerGroup.cpp
index 9be58ba7b54fa3d5270dc69ce2af40bbf0b4fa67..244e446786308adcc269bbfc84a72e05c5704e13 100644
--- a/Source/core/layout/MultiColumnFragmentainerGroup.cpp
+++ b/Source/core/layout/MultiColumnFragmentainerGroup.cpp
@@ -536,7 +536,7 @@ unsigned MultiColumnFragmentainerGroup::columnIndexAtOffset(LayoutUnit offsetInF
     }
 
     if (m_columnHeight)
-        return (offsetInFlowThread - m_logicalTopInFlowThread).toFloat() / m_columnHeight.toFloat();
+        return ((offsetInFlowThread - m_logicalTopInFlowThread) / m_columnHeight).floor();
     return 0;
 }