Don't eat margins when column height isn't yet known.

Source/core/layout/LayoutBlock.h

Index: Source/core/layout/LayoutBlock.h
diff --git a/Source/core/layout/LayoutBlock.h b/Source/core/layout/LayoutBlock.h
index 21987fa70ce502c1e846185b9f1602e77ed7e79f..c9c995d4ed8cbba30c4744fdcbc3c2ca1564f9b4 100644
--- a/Source/core/layout/LayoutBlock.h
+++ b/Source/core/layout/LayoutBlock.h
@@ -412,6 +412,8 @@ private:
     bool widthAvailableToChildrenHasChanged();
 
 protected:
+    bool isPageLogicalHeightKnown(LayoutUnit logicalOffset) const { return pageLogicalHeightForOffset(logicalOffset); }
+
     // Returns the logicalOffset at the top of the next page. If the offset passed in is already at the top of the current page,
     // then nextPageLogicalTop with ExcludePageBoundary will still move to the top of the next page. nextPageLogicalTop with
     // IncludePageBoundary set will not.