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

Source/core/rendering/RenderGrid.cpp

Index: Source/core/rendering/RenderGrid.cpp
diff --git a/Source/core/rendering/RenderGrid.cpp b/Source/core/rendering/RenderGrid.cpp
index 34d53829df9dd334440561c02d95303804da49bc..4692328710f567785e2d1a56a8d4ac5b687bbac7 100644
--- a/Source/core/rendering/RenderGrid.cpp
+++ b/Source/core/rendering/RenderGrid.cpp
@@ -618,10 +618,13 @@ void RenderGrid::distributeSpaceToTracks(Vector<GridTrack*>& tracks, Vector<Grid
         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));
-        // 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;
+        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.

[Julien - ping for review, 2013/11/05 16:16:43]

Unneeded space

+        if (growthShare > 0) {
+            sizingData.distributeTrackVector[i] += growthShare;
+            availableLogicalSpace -= growthShare;
+        }
     }
 
     if (availableLogicalSpace > 0 && tracksForGrowthAboveMaxBreadth) {