[CSS Grid Layout] Fix grid position resolution

• Component: CSS
• Status: RESOLVED FIXED

[Sergio Villar Senin]

Neither grid-{column|row}-end nor negative values are properly handled in our resolution code right now.

In order to fix it we should merge these 3 changes:

---
    r148833
    Fix the grid-{end|after} position resolution
    
    Our resolution code was resolving both positions in the same way
    but that doesn't work: in grid-rows: 2 / 3, the 2 lines, even if
    they are different numbers, refers to the same grid position so
    using the same formula to resolve them cannot work.

---
    r148878
   Refactor grid size estimation to use resolveGridPositionsFromStyle
    
    resolveGridPositionsFromStyle required to have the grid filled so that
    we resolve negative indexes against the grid's final edge. The
    specification (and the code) changed to use the 'explicit grid' which
    is independent of the grid items and depends only on the style.

---
    r150403
    This change just fixes resolveGridPositionFromStyle to handle the
    negative grid position properly. While at it, factored the position
    adjustment logic into adjustGridPostionForSide.

[Sergio Villar Senin]

Created attachment 209342 [details]
Patch

[Sergio Villar Senin]

The final patch is not a direct merge of the three patches from Blink. I removed some stuff (like tests with span and negative indexes) that will be included in future patches (like in the one for 119756).

[Andreas Kling]

Comment on attachment 209342 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=209342&action=review

> Source/WebCore/ChangeLog:16
> +        resolveGridPositionsFormStyle() so we can use it for the grid size

Typo, resolveGridPositions_From_Style.

> Source/WebCore/rendering/RenderGrid.cpp:768
> +        ASSERT(position.integerPosition());

This is a well-placed assert. I was worried about negative values here.

[Sergio Villar Senin]

Committed r154731: <http://trac.webkit.org/changeset/154731>