[CSSGridLayout] Resolved value of grid-template-* to include every track

Source/core/css/CSSComputedStyleDeclaration.cpp

Index: Source/core/css/CSSComputedStyleDeclaration.cpp
diff --git a/Source/core/css/CSSComputedStyleDeclaration.cpp b/Source/core/css/CSSComputedStyleDeclaration.cpp
index d2aae7dff888c26e3357ccb41d925bf2ef766978..b764569d33f6cb7c011fd7d07e24c6adce3ae218 100644
--- a/Source/core/css/CSSComputedStyleDeclaration.cpp
+++ b/Source/core/css/CSSComputedStyleDeclaration.cpp
@@ -887,21 +887,30 @@ static PassRefPtrWillBeRawPtr<CSSValue> valueForGridTrackList(GridTrackSizingDir
 {
     const Vector<GridTrackSize>& trackSizes = direction == ForColumns ? style.gridTemplateColumns() : style.gridTemplateRows();
     const OrderedNamedGridLines& orderedNamedGridLines = direction == ForColumns ? style.orderedNamedGridColumnLines() : style.orderedNamedGridRowLines();
+    bool isRenderGrid = renderer && renderer->isRenderGrid();
+
+    // Handle the 'none' case.
+    bool trackListIsEmpty = trackSizes.isEmpty();
+    if (isRenderGrid && trackListIsEmpty) {
+        // For grids we should consider every listed track, whether implicitly or explicitly created. If we don't have
+        // any explicit track and there are no children then there are no implicit tracks. We cannot simply check the
+        // number of rows/columns in our internal grid representation because it's always at least 1x1 (see r143331).
+        trackListIsEmpty = !toRenderBlock(renderer)->firstChild();
+    }
 
-    // Handle the 'none' case here.
-    if (!trackSizes.size()) {
+    if (trackListIsEmpty) {
         ASSERT(orderedNamedGridLines.isEmpty());
         return cssValuePool().createIdentifierValue(CSSValueNone);
     }
 
     RefPtrWillBeRawPtr<CSSValueList> list = CSSValueList::createSpaceSeparated();
-    if (renderer && renderer->isRenderGrid()) {
+    if (isRenderGrid) {
         const Vector<LayoutUnit>& trackPositions = direction == ForColumns ? toRenderGrid(renderer)->columnPositions() : toRenderGrid(renderer)->rowPositions();
         // There are at least #tracks + 1 grid lines (trackPositions). Apart from that, the grid container can generate implicit grid tracks,
         // so we'll have more trackPositions than trackSizes as the latter only contain the explicit grid.
         ASSERT(trackPositions.size() - 1 >= trackSizes.size());
 
-        for (size_t i = 0; i < trackSizes.size(); ++i) {
+        for (size_t i = 0; i < trackPositions.size() - 1; ++i) {
             addValuesForNamedGridLinesAtIndex(orderedNamedGridLines, i, *list);
             list->append(zoomAdjustedPixelValue(trackPositions[i + 1] - trackPositions[i], style));
         }