Add assert that updateLayoutTree clears dirty bits.

Source/core/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 1665 matching lines @@
                 body->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::WritingModeChange));
         }
     }
 
     if (const ComputedStyle* style = documentElement()->computedStyle()) {
         if (style->direction() != rootDirection || style->writingMode() != rootWritingMode)
             documentElement()->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::WritingModeChange));
     }
 }
 
+#if ENABLE(ASSERT)
+static void assertLayoutTreeUpdated(Node& root)
+{
+    for (Node& node : NodeTraversal::inclusiveDescendantsOf(root)) {
+        // We leave some nodes with dirty bits in the tree because they don't
+        // matter like Comment and ProcessingInstruction nodes.
+        if (!node.isElementNode()
+            && !node.isTextNode()
+            && !node.isShadowRoot()
+            && !node.isDocumentNode())
+            continue;
+
+        ASSERT(!node.needsStyleRecalc());
+        ASSERT(!node.childNeedsStyleRecalc());
+        ASSERT(!node.childNeedsDistributionRecalc());
+        ASSERT(!node.needsStyleInvalidation());
+        ASSERT(!node.childNeedsStyleInvalidation());
+
+        for (ShadowRoot* shadowRoot = node.youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot())
+            assertLayoutTreeUpdated(*shadowRoot);
+    }
+}
+#endif
+
 void Document::updateLayoutTree(StyleRecalcChange change)
 {
     ASSERT(isMainThread());
 
     ScriptForbiddenScope forbidScript;
 
     if (!view() || !isActive())
         return;
 
     if (change != Force && !needsLayoutTreeUpdate())
@@ skipping 45 matching lines @@
     // detached (for example, by setting display:none in the :hover style), schedule another mouseMove event
     // to check if any other elements ended up under the mouse pointer due to re-layout.
     if (hoverNode() && !hoverNode()->layoutObject() && frame())
         frame()->eventHandler().dispatchFakeMouseMoveEventSoon();
 
     if (m_focusedElement && !m_focusedElement->isFocusable())
         clearFocusedElementSoon();
 
     ASSERT(!m_timeline->hasOutdatedAnimation());
 
+#if ENABLE(ASSERT)
+    assertLayoutTreeUpdated(*this);
+#endif
+
     TRACE_EVENT_END1(TRACE_DISABLED_BY_DEFAULT("devtools.timeline"), "RecalculateStyles", "elementCount", m_styleRecalcElementCounter);
     TRACE_EVENT_END1("blink", "Document::updateLayoutTree", "elementCount", m_styleRecalcElementCounter);
     InspectorInstrumentation::didRecalculateStyle(cookie, m_styleRecalcElementCounter);
 }
 
 void Document::updateStyle(StyleRecalcChange change)
 {
     TRACE_EVENT_BEGIN0("blink,blink_style", "Document::updateStyle");
     unsigned initialResolverAccessCount = styleEngine().resolverAccessCount();
 
@@ skipping 3926 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif