Remove ShadowDOMV1 runtime flag (status=stable)

third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc.
  * All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
@@ skipping 447 matching lines @@
     matchElementScopeRules(element, elementScopeResolver, collector);
 }
 
 void StyleResolver::matchAuthorRules(const Element& element,
                                      ElementRuleCollector& collector) {
   if (document().shadowCascadeOrder() != ShadowCascadeOrder::ShadowCascadeV1) {
     matchAuthorRulesV0(element, collector);
     return;
   }
 
-  DCHECK(RuntimeEnabledFeatures::shadowDOMV1Enabled());
   matchHostRules(element, collector);
   matchScopedRules(element, collector);
 }
 
 void StyleResolver::matchAuthorRulesV0(const Element& element,
                                        ElementRuleCollector& collector) {
   collector.clearMatchedRules();
 
   CascadeOrder cascadeOrder = 0;
   HeapVector<Member<ScopedStyleResolver>, 8> resolversInShadowTree;
@@ skipping 1405 matching lines @@
   visitor->trace(m_viewportDependentMediaQueryResults);
   visitor->trace(m_deviceDependentMediaQueryResults);
   visitor->trace(m_selectorFilter);
   visitor->trace(m_styleSharingLists);
   visitor->trace(m_pendingStyleSheets);
   visitor->trace(m_document);
   visitor->trace(m_tracker);
 }
 
 }  // namespace blink