Take continuation into consideration when calculating absoluteClippedOverflowRect.

Source/core/rendering/RenderInline.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1002 matching lines @@
     LayoutUnit logicalTop = firstLineBox()->logicalTopVisualOverflow(firstRootBox.lineTop());
     LayoutUnit logicalWidth = logicalRightSide - logicalLeftSide;
     LayoutUnit logicalHeight = lastLineBox()->logicalBottomVisualOverflow(lastRootBox.lineBottom()) - logicalTop;
 
     LayoutRect rect(logicalLeftSide, logicalTop, logicalWidth, logicalHeight);
     if (!style()->isHorizontalWritingMode())
         rect = rect.transposedRect();
     return rect;
 }
 
+LayoutRect RenderInline::absoluteClippedOverflowRect() const
+{
+    if (!continuation())
+        return clippedOverflowRectForPaintInvalidation(view());
+
+    FloatRect floatResult;
+    LinesBoundingBoxGeneratorContext context(floatResult);
+
+    RenderInline* endContinuation = inlineElementContinuation();
+    while (endContinuation->inlineElementContinuation())
+        endContinuation = endContinuation->inlineElementContinuation();
+
+    // Note the following algorithm is N^2 (if the continuation is N renderers and the averagae
+    // depth of those renderers is M, we'll visit N*M nodes). We can possibly do some optimizations,
+    // such as mapping all these rects into a common ancestor's address space then mapping the
+    // result into the view.
+    for (RenderBlock* currBlock = containingBlock(); currBlock && currBlock->isAnonymousBlock(); currBlock = toRenderBlock(currBlock->nextSibling())) {
+        for (RenderObject* curr = currBlock->firstChild(); curr; curr = curr->nextSibling()) {
+            LayoutRect rect = curr->clippedOverflowRectForPaintInvalidation(view());
+            context(FloatRect(enclosingIntRect(rect)));

[leviw_travelin_and_unemployed, 2015/01/20 20:19:24]

If you're eventually taking the enclosingIntRect of the result (on L1044), this
enclosingIntRect is extra work.

[c.shu, 2015/01/20 23:10:22]

Done.

+            if (curr == endContinuation)
+                return enclosingIntRect(floatResult);
+        }
+    }
+    return LayoutRect();
+}
+
 LayoutRect RenderInline::clippedOverflowRectForPaintInvalidation(const RenderLayerModelObject* paintInvalidationContainer, const PaintInvalidationState* paintInvalidationState) const
 {
     if ((!firstLineBoxIncludingCulling() && !continuation()) || style()->visibility() != VISIBLE)
         return LayoutRect();
 
     LayoutRect paintInvalidationRect(linesVisualOverflowBoundingBox());
 
     LayoutUnit outlineSize = style()->outlineSize();
     paintInvalidationRect.inflate(outlineSize);
 
@@ skipping 375 matching lines @@
         container = this;
 
     FloatPoint absPos = container->localToAbsolute();
     region.bounds.setX(absPos.x() + region.bounds.x());
     region.bounds.setY(absPos.y() + region.bounds.y());
 
     regions.append(region);
 }
 
 } // namespace blink