Setting -webkit-column-count to auto is the same as not setting it.

Source/core/style/ComputedStyle.h

Index: Source/core/style/ComputedStyle.h
diff --git a/Source/core/style/ComputedStyle.h b/Source/core/style/ComputedStyle.h
index 355492e72ef692943eafab401d1c2d8ffa2e7e03..cfff496fbc4b58298db2002e1272877d2b935396 100644
--- a/Source/core/style/ComputedStyle.h
+++ b/Source/core/style/ComputedStyle.h
@@ -1295,7 +1295,7 @@ public:
     void setColumnWidth(float f) { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_autoWidth, false); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_width, f); }
     void setHasAutoColumnWidth() { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_autoWidth, true); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_width, 0); }
     void setColumnCount(unsigned short c) { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_autoCount, false); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_count, c); }
-    void setHasAutoColumnCount() { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_autoCount, true); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_count, 0); }
+    void setHasAutoColumnCount() { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_autoCount, true); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_count, initialColumnCount()); }
     void setColumnFill(ColumnFill columnFill) { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_fill, columnFill); }
     void setColumnGap(float f) { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_normalGap, false); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_gap, f); }
     void setHasNormalColumnGap() { SET_VAR(rareNonInheritedData.access()->m_multiCol, m_normalGap, true); SET_VAR(rareNonInheritedData.access()->m_multiCol, m_gap, 0); }