Fix issue in which removing a class does not always invalidate style

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 362 matching lines @@
             Element* childElement = toElement(child);
             bool childRecalced = invalidateStyleForClassChange(childElement, invalidationClasses, foundInvalidationSet);
             someChildrenNeedStyleRecalc = someChildrenNeedStyleRecalc || childRecalced;
         }
     }
     return someChildrenNeedStyleRecalc;
 }
 
 bool RuleFeatureSet::invalidateStyleForClassChange(Element* element, Vector<AtomicString>& invalidationClasses, bool foundInvalidationSet)
 {
+    bool thisElementNeedsStyleRecalc = false;
     int oldSize = invalidationClasses.size();
+
     if (element->needsStyleInvalidation()) {
-        if (InvalidationList* invalidationList = m_pendingInvalidationMap.get(element)) {
-            foundInvalidationSet = true;
-            for (InvalidationList::const_iterator it = invalidationList->begin(); it != invalidationList->end(); ++it) {
-                if ((*it)->wholeSubtreeInvalid()) {
-                    element->setNeedsStyleRecalc(SubtreeStyleChange);
-                    invalidationClasses.remove(oldSize, invalidationClasses.size() - oldSize);
-                    element->clearChildNeedsStyleInvalidation();
-                    return true;
-                }
-                (*it)->getClasses(invalidationClasses);
+        InvalidationList* invalidationList = m_pendingInvalidationMap.get(element);
+        ASSERT(invalidationList);
+        // FIXME: it's really only necessary to clone the render style for this element, not full style recalc.
+        thisElementNeedsStyleRecalc = true;
+        foundInvalidationSet = true;
+        for (InvalidationList::const_iterator it = invalidationList->begin(); it != invalidationList->end(); ++it) {
+            if ((*it)->wholeSubtreeInvalid()) {
+                element->setNeedsStyleRecalc(SubtreeStyleChange);
+                invalidationClasses.remove(oldSize, invalidationClasses.size() - oldSize);
+                element->clearChildNeedsStyleInvalidation();
+                return true;
             }
+            (*it)->getClasses(invalidationClasses);
         }
     }
 
-    bool thisElementNeedsStyleRecalc = false;
-
     if (element->hasClass()) {
         const SpaceSplitString& classNames = element->classNames();
         for (Vector<AtomicString>::const_iterator it = invalidationClasses.begin(); it != invalidationClasses.end(); ++it) {
             if (classNames.contains(*it)) {
                 thisElementNeedsStyleRecalc = true;
                 break;
             }
         }
     }
 
     // foundInvalidationSet will be true if we are in a subtree of a node with a DescendantInvalidationSet on it.
     // We need to check all nodes in the subtree of such a node.
     if (foundInvalidationSet || element->childNeedsStyleInvalidation()) {
         bool someChildrenNeedStyleRecalc = invalidateStyleForClassChangeOnChildren(element, invalidationClasses, foundInvalidationSet);
         // We only need to possibly recalc style if this node is in the subtree of a node with a DescendantInvalidationSet on it.
+        // FIXME: it's really only necessary to clone the render style for this element, not full style recalc.
         if (foundInvalidationSet)
             thisElementNeedsStyleRecalc = thisElementNeedsStyleRecalc || someChildrenNeedStyleRecalc;
     }
 
     if (thisElementNeedsStyleRecalc)
         element->setNeedsStyleRecalc(LocalStyleChange);
 
     invalidationClasses.remove(oldSize, invalidationClasses.size() - oldSize);
     element->clearChildNeedsStyleInvalidation();
+    element->clearNeedsStyleInvalidation();
+
     return thisElementNeedsStyleRecalc;
 }
 
 } // namespace WebCore