Use SubSelector as relation on left-most selector

Source/core/css/RuleFeature.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 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/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 310 matching lines @@
             }
         }
 
         if (current->relation() == CSSSelector::SubSelector)
             continue;
 
         features.treeBoundaryCrossing = current->isShadowSelector();
         features.adjacent = current->isAdjacentSelector();
         return std::make_pair(current->tagHistory(), foundFeatures ? UseFeatures : ForceSubtree);
     }
-    return std::make_pair(nullptr, ForceSubtree);
+    return std::make_pair(nullptr,  foundFeatures ? UseFeatures : ForceSubtree);
 }
 
 // Add features extracted from the rightmost compound selector to descendant invalidation
 // sets for features found in other compound selectors.
 //
 // Style invalidation is currently supported for descendants only, not for sibling subtrees.
 // We use wholeSubtree invalidation for features found left of adjacent combinators as
 // SubtreeStyleChange will force sibling subtree recalc in
 // ContainerNode::checkForChildrenAdjacentRuleChanges.
 //
@@ skipping 268 matching lines @@
     visitor->trace(uncommonAttributeRules);
     visitor->trace(m_classInvalidationSets);
     visitor->trace(m_attributeInvalidationSets);
     visitor->trace(m_idInvalidationSets);
     visitor->trace(m_pseudoInvalidationSets);
     visitor->trace(m_styleInvalidator);
 #endif
 }
 
 } // namespace blink