parserInsertBefore and parserRemoveChild should check newChild for a parent.

Source/core/html/parser/HTMLConstructionSite.cpp

Index: Source/core/html/parser/HTMLConstructionSite.cpp
diff --git a/Source/core/html/parser/HTMLConstructionSite.cpp b/Source/core/html/parser/HTMLConstructionSite.cpp
index 487323dc18dee89d40c8c272a79e5c728eb2b2de..ed322ff4f772576ba84a706372a8677e009e8797 100644
--- a/Source/core/html/parser/HTMLConstructionSite.cpp
+++ b/Source/core/html/parser/HTMLConstructionSite.cpp
@@ -102,9 +102,6 @@ static inline void insert(HTMLConstructionSiteTask& task)
     if (isHTMLTemplateElement(*task.parent))
         task.parent = toHTMLTemplateElement(task.parent.get())->content();
 
-    if (ContainerNode* parent = task.child->parentNode())
-        parent->parserRemoveChild(*task.child);
-
     if (task.nextChild)
         task.parent->parserInsertBefore(task.child.get(), *task.nextChild);
     else
@@ -150,9 +147,6 @@ static inline void executeReparentTask(HTMLConstructionSiteTask& task)
 {
     ASSERT(task.operation == HTMLConstructionSiteTask::Reparent);
 
-    if (ContainerNode* parent = task.child->parentNode())
-        parent->parserRemoveChild(*task.child);
-
     task.parent->parserAppendChild(task.child);
 }