Simplify computation of the invalidation rect for a frame.

third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 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 154 matching lines @@
     if (m_cache)
         m_cache->clear(cacheSlot);
 
     for (PaintLayer* layer = m_layoutObject.layer()->firstChild(); layer; layer = layer->nextSibling()) {
         layer->clipper().clearClipRectsIncludingDescendants(cacheSlot);
     }
 }
 
 LayoutRect PaintLayerClipper::childrenClipRect() const
 {
+    DisableCompositingQueryAsserts disabler;

[tommycli, 2015/11/03 20:10:22]

Previous usage of this had this comment:

// FIXME: childrenClipRect relies on compositingState, which is not necessarily
up to date.	
// https://code.google.com/p/chromium/issues/detail?id=343769

Should probably preserve, since that comment helped me when I was tweaking that
code.

Why does this method suddenly need this btw?

[chrishtr, 2015/11/03 21:24:56]

Forgot to update in the latest patchset. This method can actually be deleted
now.

     // FIXME: border-radius not accounted for.
     // FIXME: Flow thread based columns not accounted for.
     PaintLayer* clippingRootLayer = clippingRootForPainting();
     LayoutRect layerBounds;
     ClipRect backgroundRect, foregroundRect;
     // Need to use uncached clip rects, because the value of 'dontClipToOverflow' may be different from the painting path (<rdar://problem/11844909>).
     ClipRectsContext context(clippingRootLayer, UncachedClipRects);
     calculateRects(context, LayoutRect(m_layoutObject.view()->unscaledDocumentRect()), layerBounds, backgroundRect, foregroundRect);
     return LayoutRect(clippingRootLayer->layoutObject()->localToAbsoluteQuad(FloatQuad(FloatRect(foregroundRect.rect()))).enclosingBoundingBox());
 }
@@ skipping 176 matching lines @@
     if (context.respectOverflowClip == IgnoreOverflowClip)
         return false;
 
     if (layer->isRootLayer() && context.respectOverflowClipForViewport == IgnoreOverflowClip)
         return false;
 
     return true;
 }
 
 } // namespace blink