Clean up paint invalidation container logic for RenderText.

Source/core/rendering/RenderText.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 1558 matching lines @@
     LayoutUnit logicalHeight = lastTextBox()->logicalBottomVisualOverflow() - logicalTop;
 
     LayoutRect rect(logicalLeftSide, logicalTop, logicalWidth, logicalHeight);
     if (!style()->isHorizontalWritingMode())
         rect = rect.transposedRect();
     return rect;
 }
 
 LayoutRect RenderText::clippedOverflowRectForPaintInvalidation(const RenderLayerModelObject* paintInvalidationContainer, const PaintInvalidationState* paintInvalidationState) const
 {
-    RenderObject* rendererToIssuePaintInvalidations = containingBlock();
-
-    // Do not cross self-painting layer boundaries.
-    RenderObject* enclosingLayerRenderer = enclosingLayer()->renderer();
-    if (enclosingLayerRenderer != rendererToIssuePaintInvalidations && !rendererToIssuePaintInvalidations->isDescendantOf(enclosingLayerRenderer))
-        rendererToIssuePaintInvalidations = enclosingLayerRenderer;
-
-    // The renderer we chose to issue paint invalidations may be an ancestor of paintInvalidationContainer, but we need to do a paintInvalidationContainer-relative paint invalidation.
-    if (paintInvalidationContainer && paintInvalidationContainer != rendererToIssuePaintInvalidations && !rendererToIssuePaintInvalidations->isDescendantOf(paintInvalidationContainer))
-        return paintInvalidationContainer->clippedOverflowRectForPaintInvalidation(paintInvalidationContainer, paintInvalidationState);
-
+    const RenderObject* rendererToIssuePaintInvalidations = containingObjectForPaintInvalidation();
     return rendererToIssuePaintInvalidations->clippedOverflowRectForPaintInvalidation(paintInvalidationContainer, paintInvalidationState);
 }
 
+const RenderLayerModelObject* RenderText::containingObjectForPaintInvalidation() const
+{
+    RenderLayerModelObject* rendererToIssuePaintInvalidations = containingBlock();
+
+    // Do not cross self-painting layer boundaries.
+    RenderLayer* layer = enclosingLayer();
+    if (layer) {
+        RenderLayerModelObject* enclosingLayerRenderer = layer->renderer();
+        if (enclosingLayerRenderer != rendererToIssuePaintInvalidations && !rendererToIssuePaintInvalidations->isDescendantOf(enclosingLayerRenderer))
+            rendererToIssuePaintInvalidations = enclosingLayerRenderer;
+    }
+    return rendererToIssuePaintInvalidations;
+}
+
+const RenderLayerModelObject* RenderText::containerForPaintInvalidation() const
+{
+    const RenderObject* rendererToIssuePaintInvalidations = containingObjectForPaintInvalidation();
+    if (rendererToIssuePaintInvalidations)
+        return rendererToIssuePaintInvalidations->containerForPaintInvalidation();
+    // This can happen for detached render subtrees.
+    return 0;
+}
+
 LayoutRect RenderText::selectionRectForPaintInvalidation(const RenderLayerModelObject* paintInvalidationContainer, bool clipToVisibleContent)
 {
     ASSERT(!needsLayout());
 
     if (selectionState() == SelectionNone)
         return LayoutRect();
     RenderBlock* cb = containingBlock();
     if (!cb)
         return LayoutRect();
 
@@ skipping 270 matching lines @@
     }
     secureTextTimer->restartWithNewText(lastTypedCharacterOffset);
 }
 
 PassRefPtr<AbstractInlineTextBox> RenderText::firstAbstractInlineTextBox()
 {
     return AbstractInlineTextBox::getOrCreate(this, m_firstTextBox);
 }
 
 } // namespace blink