[css-grid] Fix performance regression in grid layout

third_party/WebKit/Source/core/layout/LayoutGrid.cpp

 /*
  * Copyright (C) 2011 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 654 matching lines @@
     // 1. Initialize per Grid track variables.
     for (size_t i = 0; i < tracks.size(); ++i) {
         GridTrack& track = tracks[i];
         GridTrackSize trackSize = gridTrackSize(direction, i, sizingData.sizingOperation);
 
         track.setBaseSize(computeUsedBreadthOfMinLength(trackSize, maxSize));
         track.setGrowthLimit(computeUsedBreadthOfMaxLength(trackSize, track.baseSize(), maxSize));
         track.setInfinitelyGrowable(false);
 
         if (trackSize.isFitContent()) {
-            GridLength gridLength = trackSize.length();
+            GridLength gridLength = trackSize.fitContentTrackBreadth();
             if (!gridLength.hasPercentage() || hasDefiniteFreeSpace)
                 track.setGrowthLimitCap(valueForLength(gridLength.length(), maxSize));
         }
 
         if (trackSize.isContentSized())
             sizingData.contentSizedTracksIndex.append(i);
         if (trackSize.maxTrackBreadth().isFlex())
             flexibleSizedTracksIndex.append(i);
     }
 
@@ skipping 451 matching lines @@
     else if (trackSize.hasMaxContentMinTrackBreadth())
         track.setBaseSize(std::max(track.baseSize(), maxContentForChild(gridItem, direction, sizingData)));
     else if (trackSize.hasAutoMinTrackBreadth())
         track.setBaseSize(std::max(track.baseSize(), minSizeForChild(gridItem, direction, sizingData)));
 
     if (trackSize.hasMinContentMaxTrackBreadth()) {
         track.setGrowthLimit(std::max(track.growthLimit(), minContentForChild(gridItem, direction, sizingData)));
     } else if (trackSize.hasMaxContentOrAutoMaxTrackBreadth()) {
         LayoutUnit growthLimit = maxContentForChild(gridItem, direction, sizingData);
         if (trackSize.isFitContent()) {
-            DCHECK(trackSize.length().isLength());
-            growthLimit = std::min(growthLimit, valueForLength(trackSize.length().length(), sizingData.availableSpace()));
+            DCHECK(trackSize.fitContentTrackBreadth().isLength());

[Manuel Rego, 2016/09/07 10:56:47]

Probably this DCHECK() is not really useful anymore.

[svillar, 2016/09/07 16:27:51]

Right.

+            growthLimit = std::min(growthLimit, valueForLength(trackSize.fitContentTrackBreadth().length(), sizingData.availableSpace()));
         }
         track.setGrowthLimit(std::max(track.growthLimit(), growthLimit));
     }
 }
 
 static LayoutUnit trackSizeForTrackSizeComputationPhase(TrackSizeComputationPhase phase, const GridTrack& track, TrackSizeRestriction restriction)
 {
     switch (phase) {
     case ResolveIntrinsicMinimums:
     case ResolveContentBasedMinimums:
@@ skipping 1499 matching lines @@
     return isOrthogonalChild(child) ? childLocation.transposedPoint() : childLocation;
 }
 
 void LayoutGrid::paintChildren(const PaintInfo& paintInfo, const LayoutPoint& paintOffset) const
 {
     if (!m_gridItemArea.isEmpty())
         GridPainter(*this).paintChildren(paintInfo, paintOffset);
 }
 
 } // namespace blink