Make compositing updates 30.7% faster for calculator

Source/core/rendering/compositing/CompositingPropertyUpdater.cpp

Index: Source/core/rendering/compositing/CompositingPropertyUpdater.cpp
diff --git a/Source/core/rendering/compositing/CompositingPropertyUpdater.cpp b/Source/core/rendering/compositing/CompositingPropertyUpdater.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..269d3eadfbc39ccb38deaeede65dbaedab8046f7
--- /dev/null
+++ b/Source/core/rendering/compositing/CompositingPropertyUpdater.cpp
@@ -0,0 +1,61 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/rendering/compositing/CompositingPropertyUpdater.h"
+
+#include "core/rendering/RenderLayer.h"
+
+namespace WebCore {
+
+CompositingPropertyUpdater::CompositingPropertyUpdater()
+    : m_geometryMap(UseTransforms)
+{
+}
+
+CompositingPropertyUpdater::~CompositingPropertyUpdater()
+{
+}
+
+void CompositingPropertyUpdater::updateAncestorDependentProperties(RenderLayer* layer, UpdateType updateType)
+{
+    if (!layer->childNeedsToUpdateAncestorDependantProperties() && updateType != ForceUpdate)
+        return;
+
+    m_geometryMap.pushMappingsToAncestor(layer, layer->parent());
+
+    if (layer->needsToUpdateAncestorDependentProperties())
+        updateType = ForceUpdate;
+
+    if (updateType == ForceUpdate) {
+        RenderLayer::AncestorDependentProperties properties;
+
+        if (!layer->isRootLayer())
+            properties.absoluteBoundingBox = enclosingIntRect(m_geometryMap.absoluteRect(layer->overlapBounds()));
+
+        layer->updateAncestorDependentProperties(properties);
+    }
+
+    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
+        updateAncestorDependentProperties(child, updateType);
+
+    m_geometryMap.popMappingsToAncestor(layer->parent());
+
+    layer->clearChildNeedsToUpdateAncestorDependantProperties();
+}
+
+#if !ASSERT_DISABLED
+
+void CompositingPropertyUpdater::assertNeedsToUpdateAncestorDependantPropertiesBitsCleared(RenderLayer* layer)
+{
+    ASSERT(!layer->childNeedsToUpdateAncestorDependantProperties());
+    ASSERT(!layer->needsToUpdateAncestorDependentProperties());
+
+    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
+        assertNeedsToUpdateAncestorDependantPropertiesBitsCleared(child);
+}
+
+#endif
+
+} // namespace WebCore