[CSS Grid] Do not grow grid tracks when the growth factor has 0 length

Source/core/rendering/RenderGrid.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 600 matching lines @@
 {
     std::sort(tracks.begin(), tracks.end(), sortByGridTrackGrowthPotential);
 
     size_t tracksSize = tracks.size();
     sizingData.distributeTrackVector.resize(tracksSize);
 
     for (size_t i = 0; i < tracksSize; ++i) {
         GridTrack& track = *tracks[i];
         LayoutUnit availableLogicalSpaceShare = availableLogicalSpace / (tracksSize - i);
         LayoutUnit trackBreadth = (tracks[i]->*trackGetter)();
-        LayoutUnit growthShare = std::max(LayoutUnit(), std::min(availableLogicalSpaceShare, track.m_maxBreadth - trackBreadth));
+        LayoutUnit growthShare = std::min(availableLogicalSpaceShare, track.m_maxBreadth - trackBreadth);
+        sizingData.distributeTrackVector[i] = trackBreadth;
         // We should never shrink any grid track or else we can't guarantee we abide by our min-sizing function.
-        sizingData.distributeTrackVector[i] = trackBreadth + growthShare;
-        availableLogicalSpace -= growthShare;
+        if (growthShare > 0) {
+            sizingData.distributeTrackVector[i] += growthShare;
+            availableLogicalSpace -= growthShare;
+        }
     }
 
     if (availableLogicalSpace > 0 && tracksForGrowthAboveMaxBreadth) {
         tracksSize = tracksForGrowthAboveMaxBreadth->size();
         for (size_t i = 0; i < tracksSize; ++i) {
             LayoutUnit growthShare = availableLogicalSpace / (tracksSize - i);
             sizingData.distributeTrackVector[i] += growthShare;
             availableLogicalSpace -= growthShare;
         }
     }
@@ skipping 505 matching lines @@
     if (isOutOfFlowPositioned())
         return "RenderGrid (positioned)";
     if (isAnonymous())
         return "RenderGrid (generated)";
     if (isRelPositioned())
         return "RenderGrid (relative positioned)";
     return "RenderGrid";
 }
 
 } // namespace WebCore