[CSS Grid Layout] Percentages of indefinite sizes should compute to "auto"

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 68f2e3e6d425ab54323c3128dda9775cc08c2d17..f2116da8df59f9aeb9ef6c5847e2e4a869127ea2 100644
--- a/Source/core/rendering/RenderGrid.cpp
+++ b/Source/core/rendering/RenderGrid.cpp
@@ -488,7 +488,17 @@ const GridTrackSize& RenderGrid::gridTrackSize(GridTrackSizingDirection directio
     if (i >= trackStyles.size())
         return (direction == ForColumns) ? style()->gridAutoColumns() : style()->gridAutoRows();
 
-    return trackStyles[i];
+    const GridTrackSize& trackSize = trackStyles[i];
+    // If the logical width/height of the grid container is indefinite, percentage values are treated as <auto>.
+    if (trackSize.isPercentage()) {
+        Length logicalSize = direction == ForColumns ? style()->logicalWidth() : style()->logicalHeight();
+        if (logicalSize.isIntrinsic()) {

[ojan, 2013/12/10 22:53:26]

Should this be isInstrinsicOrAuto? Also, what if it's a percentage that resolves
to auto? Should the nested percentage compute to auto as well?

[svillar, 2013/12/16 17:46:51]

Yeah I guess auto should be considered here as indefinite size as well.

Regarding your other questions I think I don't get exactly what you mean. We're
talking about row/column sizes which are specified once per grid in
grid-template-columns/rows properties. If we insert an item sized using
percentages into the grid it should work as if it weren't inside a grid,
whatever the expected behavior is. This is just an exception to the general
rule.

+            DEFINE_STATIC_LOCAL(GridTrackSize, autoTrackSize, (Auto));

[ojan, 2013/12/10 22:53:26]

I don't expect you gain anything here by making this a static. I think you can
just return Auto directly.

[svillar, 2013/12/16 17:46:51]

Well, we need to return a reference to a GridTrackSize object with Auto sizing,
why would we want to create a new object everytime?

+            return autoTrackSize;
+        }
+    }
+
+    return trackSize;
 }
 
 size_t RenderGrid::explicitGridColumnCount() const