[CSS Grid Layout] Named grid line span not allowed for automatic positions

[CSS Grid Layout] Named grid line span not allowed for automatic positions

From the grid layout spec we can extract the following sentence:
"If the grid item has an automatic position and a grid span for a named
line in a given dimension, instead treat the grid span as one."

The main reason is that as you don't know where the item is going to be
placed (because of it's auto-positioned), spanning to a particular line
makes no sense.

Updated GridResolvedPosition code to include this restriction when
resolving positions.

Adapted auto-placement algorithm implementation in RenderGrid as now
it's possible to pass row and column spans to
GridIterator::nextEmptyGridArea() simplifying the code.

Updated layout test to the new behavior.

BUG=353789
TEST=fast/css-grid-layout/grid-item-auto-placement-automatic-span.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176295

[Manuel Rego, 2014-06-06 21:19:29]

This week I realized about a sentence in the CSS Grid Layout spec that 
removes the possibility to use a named grid line span in an auto-placed
item.
So I'm adapting the auto-placement implementation to remove this 
possibility. I'm simply updating the values of the current layout test,
but I could create a new one if needed.

BTW, I've confirmed that this is right with the CSS WG: 
http://lists.w3.org/Archives/Public/www-style/2014Jun/0040.html

[Julien - ping for review, 2014-06-16 20:31:35]

lgtm

https://codereview.chromium.org/320093002/diff/1/Source/core/rendering/Render...
File Source/core/rendering/RenderGrid.cpp (right):

https://codereview.chromium.org/320093002/diff/1/Source/core/rendering/Render...
Source/core/rendering/RenderGrid.cpp:912: GridSpan majorAxisPositions =
GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(),
*gridItem, autoPlacementMajorAxisDirection(), GridResolvedPosition(0));
This line is now common to the 2 branches and it could be moved above.

[Manuel Rego, 2014-06-16 21:15:34]

Thanks for the review.

https://codereview.chromium.org/320093002/diff/1/Source/core/rendering/Render...
File Source/core/rendering/RenderGrid.cpp (right):

https://codereview.chromium.org/320093002/diff/1/Source/core/rendering/Render...
Source/core/rendering/RenderGrid.cpp:912: GridSpan majorAxisPositions =
GridResolvedPosition::resolveGridPositionsFromAutoPlacementPosition(*style(),
*gridItem, autoPlacementMajorAxisDirection(), GridResolvedPosition(0));
On 2014/06/16 20:31:35, Julien Chaffraix - PST wrote:
> This line is now common to the 2 branches and it could be moved above.

Yeah, you're right. I'm moving it outside the if.

[Manuel Rego, 2014-06-16 21:15:39]

The CQ bit was checked by rego@igalia.com

[commit-bot: I haz the power, 2014-06-16 21:16:39]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/rego@igalia.com/320093002/20001

[commit-bot: I haz the power, 2014-06-16 23:38:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-06-16 23:38:59]

Try jobs failed on following builders:
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/12179)

[Manuel Rego, 2014-06-17 07:15:57]

The CQ bit was checked by rego@igalia.com

[commit-bot: I haz the power, 2014-06-17 07:16:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/rego@igalia.com/320093002/20001

[commit-bot: I haz the power, 2014-06-17 08:08:30]

Change committed as 176295