No need to detect change in size when opting for PositionedMovementLayout

Source/core/rendering/RenderBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 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 489 matching lines @@
     void logicalExtentAfterUpdatingLogicalWidth(const LayoutUnit& logicalTop, LogicalExtentComputedValues&);
 
     // Called when a positioned object moves but doesn't necessarily change size.  A simplified layout is attempted
     // that just updates the object's position. If the size does change, the object remains dirty.
     bool tryLayoutDoingPositionedMovementOnly()
     {
         LayoutUnit oldWidth = logicalWidth();
         LogicalExtentComputedValues computedValues;
         logicalExtentAfterUpdatingLogicalWidth(logicalTop(), computedValues);
         // If we shrink to fit our width may have changed, so we still need full layout.
-        // FIXME: We check for potential change of width when deciding to set needsPositionedMovementLayout.
-        // So either that check or this one is unnecessary, probably the former. crbug.com/428050
         if (oldWidth != computedValues.m_extent)
             return false;
         setLogicalWidth(computedValues.m_extent);
         setLogicalLeft(computedValues.m_position);
         setMarginStart(computedValues.m_margins.m_start);
         setMarginEnd(computedValues.m_margins.m_end);
         updateLogicalHeight();
         return true;
     }
 
@@ skipping 293 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace blink
 
 #endif // RenderBox_h