Remove the ENABLE_IFRAME_SEAMLESS compile-time flag.

Source/WebCore/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 5735 matching lines @@
     if (!shouldDisplaySeamlesslyWithParent())
         return 0;
 
     HTMLFrameOwnerElement* ownerElement = this->ownerElement();
     ASSERT(ownerElement->hasTagName(iframeTag));
     return static_cast<HTMLIFrameElement*>(ownerElement);
 }
 
 bool Document::shouldDisplaySeamlesslyWithParent() const
 {
-#if ENABLE(IFRAME_SEAMLESS)
     if (!RuntimeEnabledFeatures::seamlessIFramesEnabled())
         return false;
     HTMLFrameOwnerElement* ownerElement = this->ownerElement();
     if (!ownerElement)
         return false;
     return m_mayDisplaySeamlesslyWithParent && ownerElement->hasTagName(iframeTag) && ownerElement->fastHasAttribute(seamlessAttr);
-#else
-    return false;
-#endif
 }
 
 DocumentLoader* Document::loader() const
 {
     if (!m_frame)
         return 0;
     
     DocumentLoader* loader = m_frame->loader()->documentLoader();
     if (!loader)
         return 0;
@@ skipping 389 matching lines @@
         return;
 
     Vector<RefPtr<Element> > associatedFormControls;
     copyToVector(m_associatedFormControls, associatedFormControls);
 
     frame()->page()->chrome()->client()->didAssociateFormControls(associatedFormControls);
     m_associatedFormControls.clear();
 }
 
 } // namespace WebCore