Clean up creation of "detached" SVG* data type objects

third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h

Index: third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h
diff --git a/third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h b/third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h
index f93c924e7b1b6ed831085c19ceb2b86cff78d16c..ba394ef4cf878a3a4c070cc4f321dd963c50ccb2 100644
--- a/third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h
+++ b/third_party/WebKit/Source/core/svg/SVGNumberListTearOff.h
@@ -46,7 +46,7 @@ class SVGNumberListTearOff final
       SVGNumberList* target,
       SVGElement* context_element,
       PropertyIsAnimValType property_is_anim_val,
-      const QualifiedName& attribute_name = QualifiedName::Null()) {
+      const QualifiedName& attribute_name) {
     return new SVGNumberListTearOff(target, context_element,
                                     property_is_anim_val, attribute_name);
   }
@@ -56,11 +56,10 @@ class SVGNumberListTearOff final
   }
 
  private:
-  SVGNumberListTearOff(
-      SVGNumberList* target,
-      SVGElement* context_element,
-      PropertyIsAnimValType property_is_anim_val,
-      const QualifiedName& attribute_name = QualifiedName::Null())
+  SVGNumberListTearOff(SVGNumberList* target,
+                       SVGElement* context_element,
+                       PropertyIsAnimValType property_is_anim_val,
+                       const QualifiedName& attribute_name)
       : SVGListPropertyTearOffHelper<SVGNumberListTearOff, SVGNumberList>(
             target,
             context_element,