[css-grid] Avoid computing available space if gap is not a percentage

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 514 matching lines @@
 
 bool LayoutGrid::isEmptyAutoRepeatTrack(GridTrackSizingDirection direction, size_t line) const
 {
     DCHECK(hasAutoRepeatEmptyTracks(direction));
     return direction == ForColumns ? m_autoRepeatEmptyColumns->contains(line) : m_autoRepeatEmptyRows->contains(line);
 }
 
 LayoutUnit LayoutGrid::gridGapForDirection(GridTrackSizingDirection direction, SizingOperation sizingOperation) const
 {
     LayoutUnit availableSize;
-    if (sizingOperation == TrackSizing)
+    const Length& gap = direction == ForColumns ? styleRef().gridColumnGap() : styleRef().gridRowGap();
+    if (sizingOperation == TrackSizing && gap.isPercent())
         availableSize = direction == ForColumns ? availableLogicalWidth() : availableLogicalHeightForPercentageComputation();
 
     // TODO(rego): Maybe we could cache the computed percentage as a performance improvement.
-    return valueForLength(direction == ForColumns ? styleRef().gridColumnGap() : styleRef().gridRowGap(), availableSize);
+    return valueForLength(gap, availableSize);
 }
 
 LayoutUnit LayoutGrid::guttersSize(GridTrackSizingDirection direction, size_t startLine, size_t span, SizingOperation sizingOperation) const
 {
     if (span <= 1)
         return LayoutUnit();
 
     bool isRowAxis = direction == ForColumns;
     LayoutUnit gap = gridGapForDirection(direction, sizingOperation);
 
@@ skipping 2111 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