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

LayoutTests/fast/css-grid-layout/resources/grid.css

Index: LayoutTests/fast/css-grid-layout/resources/grid.css
diff --git a/LayoutTests/fast/css-grid-layout/resources/grid.css b/LayoutTests/fast/css-grid-layout/resources/grid.css
index 0db9059060126b169b60c5b19bcac26fc694b461..b6b953bfb1fe8e6f2910fe8afc015ffb9ee11970 100644
--- a/LayoutTests/fast/css-grid-layout/resources/grid.css
+++ b/LayoutTests/fast/css-grid-layout/resources/grid.css
@@ -1,4 +1,4 @@
-.grid {
+.grid, .noSizeGrid {

[Julien - ping for review, 2013/11/07 18:18:26]

I hate this new class name. grid is not sized itself which makes the new name
very confusing. If there is a pattern in the size we use, we should have a
sizedGrid vs an unsizedGrid. If not, I would replace the broad .grid selector
with a different one (like .explicitlySized) and not apply it to the one. To
make sure we get the point though, we would have to add a comment about it being
unsized and we expect grid to ignore the percentage tracks.

[svillar, 2013/11/07 18:44:29]

OK got the point. The thing is that this is not about defining a sized vs an
unsized grid, because as you can see this selector basically just defines the
display: grid. I added it because several tests extend .grid by adding an
explicit size.

That's why not applying an hypothetic .explicitlySized is not an option because
we still want the display:. I think I'd better define an unsizedGrid.

     display: grid;
     background-color: grey;
 }