[CSS Grid Layout] Rename grid-{rows|columns} to grid-definition-{rows|columns}

LayoutTests/fast/css-grid-layout/grid-element-change-columns-repaint-expected.txt

-This test checks that changing the grid-columns lead to a repaint. The final grid element should be 250px * 50px, the grid item should be 50px * 50px. No trace of the elements before the grid-columns change should be seen.
+This test checks that changing the grid-definition-columns lead to a repaint. The final grid element should be 250px * 50px, the grid item should be 50px * 50px. No trace of the elements before the grid-definition-columns change should be seen.
 (repaint rects
-  (rect 8 38 100 50)
-  (rect 8 38 50 50)
-  (rect 8 38 250 50)
+  (rect 8 48 100 50)
+  (rect 8 48 50 50)
+  (rect 8 48 250 50)

[Julien - ping for review, 2013/06/19 22:28:25]

This change looks wrong: the repaint rectangles shouldn't change as part of this
change.

[svillar, 2013/06/20 07:17:56]

That's what I thought but the fact is that the Y value changes because the size
of the paragraph above changes. We might decide not to change the comment in the
bug but I think it's safe.

[Julien - ping for review, 2013/06/21 21:08:40]

You are right, we set the font size to 10 in this test so it looks like we have
an extra line of text before of the longer property names. I would still go
ahead with the renaming of this test as we understand the difference.

 )