Remove the forced layout in getComputedStyle for elements in Shadow DOM

third_party/WebKit/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 1884 matching lines @@
         return;
 
     m_lifecycle.advanceTo(DocumentLifecycle::InLayoutSubtreeChange);
 
     layoutView()->handleSubtreeModifications();
     ASSERT(!layoutView()->wasNotifiedOfSubtreeChange());
 
     m_lifecycle.advanceTo(DocumentLifecycle::LayoutSubtreeChangeClean);
 }
 
+static bool nodeMayNeedStyleRecalc(const ContainerNode& node)

[rune, 2016/02/01 09:24:23]

Should we now use anonymous namespace instead of static functions? I couldn't
find anything about it in the Blink coding standard or in "C++11 use in
Chromium".

+{
+    return node.needsStyleRecalc() || node.needsStyleInvalidation() || node.needsAdjacentStyleRecalc();
+}
+
+static bool nodeMayNeedStyleRecalc(const ContainerNode* node)
+{
+    return node && nodeMayNeedStyleRecalc(*node);
+}
+
 void Document::updateLayoutTreeForNodeIfNeeded(Node* node)
 {
     ASSERT(node);
     if (!node->canParticipateInComposedTree())
         return;
     if (!needsLayoutTreeUpdate())
         return;
     if (!node->inDocument())
         return;
 
     bool needsRecalc = needsFullLayoutTreeUpdate() || node->needsStyleRecalc() || node->needsStyleInvalidation();
 
     if (!needsRecalc) {
-        for (const ContainerNode* ancestor = LayoutTreeBuilderTraversal::parent(*node); ancestor && !needsRecalc; ancestor = LayoutTreeBuilderTraversal::parent(*ancestor))
-            needsRecalc = ancestor->needsStyleRecalc() || ancestor->needsStyleInvalidation() || ancestor->needsAdjacentStyleRecalc();
+        LayoutTreeBuilderTraversal::ParentDetails parentDetails;
+        for (const ContainerNode* ancestor = LayoutTreeBuilderTraversal::parent(*node, &parentDetails); ancestor && !needsRecalc; ancestor = LayoutTreeBuilderTraversal::parent(*ancestor, &parentDetails)) {
+            needsRecalc = nodeMayNeedStyleRecalc(*ancestor) || nodeMayNeedStyleRecalc(parentDetails.shadowRoot());
+            parentDetails.reset();
+        }
+        // We may have bailed out of the loop because there's no ancestor in the
+        // composed tree, but we still need to check the shadow root.
+        needsRecalc = needsRecalc || nodeMayNeedStyleRecalc(parentDetails.shadowRoot());

[rune, 2016/02/01 09:24:23]

How could that happen? Won't every shadow root have a shadow host parent so that
the when we record a shadow root, the ancestor will be the shadow host?

     }
 
     if (needsRecalc)
         updateLayoutTreeIfNeeded();
 }
 
 void Document::updateLayout()
 {
     ASSERT(isMainThread());
 
@@ skipping 3996 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     Document::WeakDocumentSet& set = Document::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