Add infrastructure for partial layouts

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 1726 matching lines @@
         oe->document()->updateLayout();
 
     updateStyleIfNeeded();
 
     StackStats::LayoutCheckPoint layoutCheckPoint;
 
     // Only do a layout if changes have occurred that make it necessary.
     if (frameView && renderer() && (frameView->layoutPending() || renderer()->needsLayout()))
         frameView->layout();
 
+    if (frameView)
+        frameView->resetPartialLayoutState();
+
     setNeedsFocusedElementCheck();
 }
 
 void Document::setNeedsFocusedElementCheck()
 {
     // FIXME: Using a Task doesn't look a good idea.
     if (!m_focusedElement || m_didPostCheckFocusedElementTask)
         return;
     postTask(CheckFocusedElementTask::create());
     m_didPostCheckFocusedElementTask = true;
@@ skipping 26 matching lines @@
             // may not have had their real style calculated yet. Normally this gets cleaned when style sheets arrive
             // but here we need up-to-date style immediately.
             recalcStyle(Force);
     }
 
     updateLayout();
 
     m_ignorePendingStylesheets = oldIgnore;
 }
 
+void Document::tryPartialUpdateLayoutIgnorePendingStylesheets(RenderObject* stopLayoutAtRenderer)
+{
+    if (stopLayoutAtRenderer) {
+        // Look for parents that are css regions, flexbox, grid, or flow and prevent partial layout.
+        // FIXME: should this be a whitelist?
+        bool canDoPartialLayout = true;
+        RenderObject* renderer = stopLayoutAtRenderer;
+        do {
+            if (renderer->isFlexibleBoxIncludingDeprecated() || renderer->isRenderGrid() || renderer->isRenderRegion() || renderer->isRenderNamedFlowThread() || renderer->isRenderFlowThread()) {
+                canDoPartialLayout = false;
+                break;
+            }
+        } while ((renderer = renderer->parent()));
+        if (canDoPartialLayout)
+            view()->setStopLayoutAtRenderer(stopLayoutAtRenderer);
+    }
+
+    updateLayoutIgnorePendingStylesheets();
+}
+
 PassRefPtr<RenderStyle> Document::styleForElementIgnoringPendingStylesheets(Element* element)
 {
     ASSERT_ARG(element, element->document() == this);
     TemporaryChange<bool> ignoreStyleSheets(m_ignorePendingStylesheets, true);
     return styleResolver()->styleForElement(element, element->parentNode() ? element->parentNode()->computedStyle() : 0);
 }
 
 PassRefPtr<RenderStyle> Document::styleForPage(int pageIndex)
 {
     return styleResolver()->styleForPage(pageIndex);
@@ skipping 3326 matching lines @@
 {
     return DocumentLifecycleNotifier::create(this);
 }
 
 DocumentLifecycleNotifier* Document::lifecycleNotifier()
 {
     return static_cast<DocumentLifecycleNotifier*>(ScriptExecutionContext::lifecycleNotifier());
 }
 
 } // namespace WebCore