[css-grid] Fix performance regression in grid layout

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

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index 0a0a80b51a7ffe268055b7b47a18f5f969f70066..d8a728cfcb90eb403809f2c75332464502308d30 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -672,7 +672,7 @@ void LayoutGrid::computeUsedBreadthOfGridTracks(GridTrackSizingDirection directi
         track.setInfinitelyGrowable(false);
 
         if (trackSize.isFitContent()) {
-            GridLength gridLength = trackSize.length();
+            GridLength gridLength = trackSize.fitContentTrackBreadth();
             if (!gridLength.hasPercentage() || hasDefiniteFreeSpace)
                 track.setGrowthLimitCap(valueForLength(gridLength.length(), maxSize));
         }
@@ -1144,8 +1144,8 @@ void LayoutGrid::resolveContentBasedTrackSizingFunctionsForNonSpanningItems(Grid
     } 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));
     }