Document lifecycle violation

third_party/WebKit/Source/core/paint/PaintLayer.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 2694 matching lines @@
     }
 
     ensureFilterInfo()->setBuilder(nullptr);
 }
 
 void PaintLayer::filterNeedsPaintInvalidation()
 {
     {
         DeprecatedScheduleStyleRecalcDuringLayout marker(layoutObject()->document().lifecycle());
         // It's possible for scheduleSVGFilterLayerUpdateHack to schedule a style recalc, which
-        // is a problem because this function can be called while performing layout.
-        // Presumably this represents an illegal data flow of layout or compositing
-        // information into the style system.
+        // is a problem because this function can be called right before performing layout but
+        // after style recalc.
+        //
+        // See LayoutView::layout() and the call to
+        // invalidateSVGRootsWithRelativeLengthDescendents(). This violation is worked around
+        // in FrameView::updateStyleAndLayoutIfNeededRecursive() by doing an extra style recalc
+        // and layout in case it's needed.
         toElement(layoutObject()->node())->scheduleSVGFilterLayerUpdateHack();
     }
 
     layoutObject()->setShouldDoFullPaintInvalidation();
 }
 
 void PaintLayer::addLayerHitTestRects(LayerHitTestRects& rects) const
 {
     computeSelfHitTestRects(rects);
     for (PaintLayer* child = firstChild(); child; child = child->nextSibling())
@@ skipping 103 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif