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

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 ea4d9ff9a84367692c6ed0672561fcf4c7a4521a..c76dd7d4fd35df8cd800ba1964120a2db2a3be4e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -532,11 +532,12 @@ bool LayoutGrid::isEmptyAutoRepeatTrack(GridTrackSizingDirection direction, size
 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