[New Multicolumn] Prevent SVG foreignObject from becoming a spanner.

Source/core/layout/LayoutMultiColumnFlowThread.cpp

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 438 matching lines @@
         m_lastSetWorkedOn = nextSet;
         nextSet->beginFlow(logicalTopInFlowThread);
     }
     return adjustment;
 }
 
 // When processing layout objects to remove or when processing layout objects that have just been
 // inserted, certain types of objects should be skipped.
 static bool shouldSkipInsertedOrRemovedChild(const LayoutObject& child)
 {
+    if (child.isSVG() && !child.isSVGRoot()) {
+        // Don't descend into SVG objects. What's in there is of no interest, and there might even
+        // be a foreignObject there with column-span:all, which doesn't apply to us.
+        return true;
+    }
     if (child.isLayoutFlowThread()) {
         // Found an inner flow thread. We need to skip it and its descendants.
         return true;
     }
     if (child.isLayoutMultiColumnSet() || child.isLayoutMultiColumnSpannerPlaceholder()) {
         // Column sets and spanner placeholders in a child multicol context don't affect the parent
         // flow thread.
         return true;
     }
     return false;
@@ skipping 241 matching lines @@
 }
 
 bool LayoutMultiColumnFlowThread::isPageLogicalHeightKnown() const
 {
     if (LayoutMultiColumnSet* columnSet = lastMultiColumnSet())
         return columnSet->pageLogicalHeight();
     return false;
 }
 
 }