Paint invalidation: Need to check offset cacheability for invalidation containers.

Source/core/rendering/PaintInvalidationState.cpp

 // 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/PaintInvalidationState.h"
 
 #include "core/rendering/RenderInline.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderView.h"
@@ skipping 26 matching lines @@
 PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& next, RenderLayerModelObject& renderer, const RenderLayerModelObject& paintInvalidationContainer)
     : m_clipped(false)
     , m_cachedOffsetsEnabled(true)
     , m_forceCheckForPaintInvalidation(next.m_forceCheckForPaintInvalidation)
     , m_paintInvalidationContainer(paintInvalidationContainer)
 {
     // FIXME: SVG could probably benefit from a stack-based optimization like html does. crbug.com/391054
     bool establishesPaintInvalidationContainer = renderer == m_paintInvalidationContainer;
     bool fixed = renderer.style()->position() == FixedPosition;
 
+    if (!renderer.supportsPaintInvalidationStateCachedOffsets() || !next.m_cachedOffsetsEnabled)
+        m_cachedOffsetsEnabled = false;
     if (establishesPaintInvalidationContainer) {
         // When we hit a new paint invalidation container, we don't need to
         // continue forcing a check for paint invalidation because movement
         // from our parents will just move the whole invalidation container.
         m_forceCheckForPaintInvalidation = false;
     } else {
-        if (!renderer.supportsPaintInvalidationStateCachedOffsets() || !next.m_cachedOffsetsEnabled) {
-            m_cachedOffsetsEnabled = false;
-        } else {
+        if (m_cachedOffsetsEnabled) {
             if (fixed) {
                 FloatPoint fixedOffset = renderer.localToContainerPoint(FloatPoint(), &m_paintInvalidationContainer, TraverseDocumentBoundaries);
                 m_paintOffset = LayoutSize(fixedOffset.x(), fixedOffset.y());
             } else {
                 LayoutSize offset = renderer.isBox() && !renderer.isTableRow() ? toRenderBox(renderer).locationOffset() : LayoutSize();
                 m_paintOffset = next.m_paintOffset + offset;
             }
 
             if (renderer.isOutOfFlowPositioned() && !fixed) {
                 if (RenderObject* container = renderer.container()) {
@@ skipping 59 matching lines @@
     // to be always invalidated in-time.
     if (box.usesCompositedScrolling())
         ASSERT(!m_clipped); // The box should establish paint invalidation container, so no m_clipped inherited.
     else
         addClipRectRelativeToPaintOffset(LayoutSize(box.layer()->size()));
 
     m_paintOffset -= box.scrolledContentOffset();
 }
 
 } // namespace blink