createElement should not transmit exceptions but report them.

third_party/WebKit/Source/core/dom/custom/CustomElementTestHelpers.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CustomElementTestHelpers_h
 #define CustomElementTestHelpers_h
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
@@ skipping 47 matching lines @@
       return false;
     constructionStack().last().clear();
     return true;
   }
 
   HTMLElement* createElementSync(Document& document,
                                  const QualifiedName&) override {
     return createElementForConstructor(document);
   }
 
-  HTMLElement* createElementSync(Document& document,
-                                 const QualifiedName&,
-                                 ExceptionState&) override {
-    return createElementForConstructor(document);
-  }
-
   bool hasConnectedCallback() const override { return false; }
   bool hasDisconnectedCallback() const override { return false; }
   bool hasAdoptedCallback() const override { return false; }
 
   void runConnectedCallback(Element*) override {
     NOTREACHED() << "definition does not have connected callback";
   }
 
   void runDisconnectedCallback(Element*) override {
     NOTREACHED() << "definition does not have disconnected callback";
@@ skipping 54 matching lines @@
  private:
   Member<Document> m_document;
   AtomicString m_namespaceURI;
   AtomicString m_localName;
   std::vector<std::pair<QualifiedName, AtomicString>> m_attributes;
 };
 
 }  // namespace blink
 
 #endif  // CustomElementTestHelpers_h