Begin tracking why layout is invalidated

Source/core/layout/LayoutVideo.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 56 matching lines @@
 
     // Never set the element size to zero when in a media document.
     if (size.isEmpty() && node()->ownerDocument() && node()->ownerDocument()->isMediaDocument())
         return;
 
     if (size == intrinsicSize())
         return;
 
     setIntrinsicSize(size);
     setPreferredLogicalWidthsDirty();
-    setNeedsLayoutAndFullPaintInvalidation();
+    setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReason::SizeChanged);
 }
 
 LayoutSize LayoutVideo::calculateIntrinsicSize()
 {
     HTMLVideoElement* video = videoElement();
 
     // Spec text from 4.8.6
     //
     // The intrinsic width of a video element's playback area is the intrinsic width
     // of the video resource, if that is available; otherwise it is the intrinsic
@@ skipping 162 matching lines @@
             return CompositingReasonVideo;
     }
 
     if (shouldDisplayVideo() && supportsAcceleratedRendering())
         return CompositingReasonVideo;
 
     return CompositingReasonNone;
 }
 
 } // namespace blink