No need for subtree recalc for :-internal-spatial-navigation-focus.

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 127 matching lines @@
     case CSSSelector::PseudoInRange:
     case CSSSelector::PseudoOutOfRange:
     case CSSSelector::PseudoWebKitCustomElement:
     case CSSSelector::PseudoCue:
     case CSSSelector::PseudoFutureCue:
     case CSSSelector::PseudoPastCue:
     case CSSSelector::PseudoUnresolved:
     case CSSSelector::PseudoContent:
     case CSSSelector::PseudoHost:
     case CSSSelector::PseudoShadow:
+    case CSSSelector::PseudoSpatialNavigationFocus:
     case CSSSelector::PseudoListBox:
         return true;
     case CSSSelector::PseudoNotParsed:
     case CSSSelector::PseudoUnknown:
     case CSSSelector::PseudoLeftPage:
     case CSSSelector::PseudoRightPage:
     case CSSSelector::PseudoFirstPage:
         // These should not appear in StyleRule selectors.
         ASSERT_NOT_REACHED();
         return false;
     default:
         // New pseudo type added. Figure out if it needs a subtree invalidation or not.
         ASSERT_NOT_REACHED();
         return false;
     }
 }
 
 #endif // ENABLE(ASSERT)
 
 static bool requiresSubtreeInvalidation(const CSSSelector& selector)
 {
     if (!selector.matchesPseudoElement() && selector.match() != CSSSelector::PseudoClass) {
         ASSERT(supportsInvalidation(selector.match()));
         return false;
     }
 
     switch (selector.pseudoType()) {
     case CSSSelector::PseudoFirstLine:
     case CSSSelector::PseudoFirstLetter:
-    case CSSSelector::PseudoSpatialNavigationFocus:
         // FIXME: Most pseudo classes/elements above can be supported and moved
         // to assertSupportedPseudo(). Move on a case-by-case basis. If they
         // require subtree invalidation, document why.
     case CSSSelector::PseudoHostContext:
         // :host-context matches a shadow host, yet the simple selectors inside
         // :host-context matches an ancestor of the shadow host.
         return true;
     default:
         ASSERT(supportsInvalidation(selector.pseudoType()));
         return false;
@@ skipping 465 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