Merge 115471 - Infinite backgroundClipRect should not be scrolled.

Source/WebCore/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 3708 matching lines @@
 }
 
 ClipRect RenderLayer::backgroundClipRect(const RenderLayer* rootLayer, RenderRegion* region, bool temporaryClipRects, OverlayScrollbarSizeRelevancy relevancy) const
 {
     ASSERT(parent());
     ClipRects parentRects;
     parentClipRects(rootLayer, region, parentRects, temporaryClipRects, relevancy);
     ClipRect backgroundClipRect = backgroundClipRectForPosition(parentRects, renderer()->style()->position());
     RenderView* view = renderer()->view();
     ASSERT(view);
-    if (parentRects.fixed() && rootLayer->renderer() == view)
+
+    // Note: infinite clipRects should not be scrolled here, otherwise they will accidentally no longer be considered infinite.
+    if (parentRects.fixed() && rootLayer->renderer() == view && backgroundClipRect != PaintInfo::infiniteRect())
         backgroundClipRect.move(view->frameView()->scrollXForFixedPosition(), view->frameView()->scrollYForFixedPosition());
+
     return backgroundClipRect;
 }
 
 void RenderLayer::calculateRects(const RenderLayer* rootLayer, RenderRegion* region, const LayoutRect& paintDirtyRect, LayoutRect& layerBounds,
                                  ClipRect& backgroundRect, ClipRect& foregroundRect, ClipRect& outlineRect, bool temporaryClipRects,
                                  OverlayScrollbarSizeRelevancy relevancy) const
 {
     if (rootLayer != this && parent()) {
         backgroundRect = backgroundClipRect(rootLayer, region, temporaryClipRects, relevancy);
         backgroundRect.intersect(paintDirtyRect);
@@ skipping 819 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif