Set default deep value false in Document.importNode

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index d03e54db7e4e17cdcc783e30bc65f1417501c5b7..a4e9fd834d21c980513d3b4472403477ee0c928f 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -733,10 +733,6 @@ String UseCounter::deprecationMessage(Feature feature)
     case RangeDetach:
         return "'Range.detach' is now a no-op, as per DOM (http://dom.spec.whatwg.org/#dom-range-detach).";
 
-    case DocumentImportNodeOptionalArgument:
-        return "The behavior of importNode() with no boolean argument is about to change from doing a deep clone to doing a shallow clone.  "
-            "Make sure to pass an explicit boolean argument to keep your current behavior.";
-
     case OverflowChangedEvent:
         return "The 'overflowchanged' event is deprecated and may be removed. Please do not use it.";