[css-grid] Fix static position for positioned grid items

[Manuel Rego Casasnovas]

The spec was updated (almost 1 year ago) to define properly
the static position of the positioned grid items:
https://drafts.csswg.org/css-grid-1/issues-wd-20150108#issue-1

But we didn't apply this change in our implementation.

The specific wording from the spec (https://drafts.csswg.org/css-grid/#static-position):
"The static position [CSS21] of an absolutely-positioned child of a grid container
 is determined as if it were the sole grid item in a grid area whose edges
 coincide with the padding edges of the grid container.
 However, if the grid container parent is also the generator of
 the absolutely positioned element’s containing block, instead use the grid area
 determined in §11.1 With a Grid Container as Containing Block."


This was already fixed in Blink:
https://codereview.chromium.org/1929483002

[Manuel Rego Casasnovas]

Created attachment 278246 [details]
Patch

[Darin Adler]

Comment on attachment 278246 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=278246&action=review

> Source/WebCore/rendering/RenderGrid.cpp:1525
> +            RenderLayer* childLayer = child.layer();

Local variable should be a reference, not a pointer.

    auto& childLayer = *child.layer();

[Manuel Rego Casasnovas]

Created attachment 278397 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 278397 [details]
Patch

Clearing flags on attachment: 278397

Committed r200572: <http://trac.webkit.org/changeset/200572>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.