Remove unused 'Credential::create' methods.

Source/modules/credentialmanager/Credential.h

 // Copyright 2014 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 Credential_h
 #define Credential_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/credentialmanager/PlatformCredential.h"
 #include "platform/heap/Handle.h"
 #include "platform/weborigin/KURL.h"
 
 namespace blink {
 
 class ExceptionState;
 
 class Credential : public GarbageCollected<Credential>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static Credential* create(const String& id, const String& name, const KURL& icon);
-    static Credential* create(const String& id, const String& name, const String& icon, ExceptionState&);
-
     // Credential.idl
     const String& id() const { return m_platformCredential->id(); }
     const String& name() const { return m_platformCredential->name(); }
     const KURL& iconURL() const { return m_platformCredential->iconURL(); }
     const String& type() const { return m_platformCredential->type(); }
 
     DECLARE_VIRTUAL_TRACE();
 
     PlatformCredential* platformCredential() const { return m_platformCredential; }
 
 protected:
     Credential(PlatformCredential*);
     Credential(const String& id, const String& name, const KURL& icon);
 
     // Parses a string as a KURL. Throws an exception via |exceptionState| if an invalid URL is produced.
     static KURL parseStringAsURL(const String&, ExceptionState&);
 
     Member<PlatformCredential> m_platformCredential;
 };
 
 } // namespace blink
 
 #endif // Credential_h