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

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

Modify LayoutGrid::prepareChildForPositionedLayout() to avoid
including padding, to match the behavior described on the spec [1]:
  "The static position 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."

The test is updated as the expected results were wrong.
Note that after this patch we match Firefox behavior on this test.

BUG=273898
TEST=fast/css-grid-layout/absolute-positioning-grid-container-parent.html

[1] https://drafts.csswg.org/css-grid/#static-position

Review-Url: https://codereview.chromium.org/2665983004
Cr-Commit-Position: refs/heads/master@{#447491}
Committed: https://chromium.googlesource.com/chromium/src/+/13f00a7b6a700f280ec590e654cdbf223c510a45

[Manuel Rego, 2017-02-01 11:07:08]

rego@igalia.com changed reviewers:
+ cbiesinger@chromium.org, jfernandez@igalia.com, svillar@igalia.com

[svillar, 2017-02-01 11:22:06]

lgtm

[Manuel Rego, 2017-02-01 11:28:15]

The CQ bit was checked by rego@igalia.com

[commit-bot: I haz the power, 2017-02-01 11:28:23]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-01 12:31:42]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1485948495322650, "parent_rev":
"286225b8d7ea0ce861bf17be58df4af7a3a5e379", "commit_rev":
"13f00a7b6a700f280ec590e654cdbf223c510a45"}

[commit-bot: I haz the power, 2017-02-01 12:36:47]

Description was changed from

==========
[css-grid] Fix static position of positioned grid items

Modify LayoutGrid::prepareChildForPositionedLayout() to avoid
including padding, to match the behavior described on the spec [1]:
  "The static position 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."

The test is updated as the expected results were wrong.
Note that after this patch we match Firefox behavior on this test.

BUG=273898
TEST=fast/css-grid-layout/absolute-positioning-grid-container-parent.html

[1] https://drafts.csswg.org/css-grid/#static-position
==========

to

==========
[css-grid] Fix static position of positioned grid items

Modify LayoutGrid::prepareChildForPositionedLayout() to avoid
including padding, to match the behavior described on the spec [1]:
  "The static position 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."

The test is updated as the expected results were wrong.
Note that after this patch we match Firefox behavior on this test.

BUG=273898
TEST=fast/css-grid-layout/absolute-positioning-grid-container-parent.html

[1] https://drafts.csswg.org/css-grid/#static-position

Review-Url: https://codereview.chromium.org/2665983004
Cr-Commit-Position: refs/heads/master@{#447491}
Committed:
https://chromium.googlesource.com/chromium/src/+/13f00a7b6a700f280ec590e654cd...
==========

[commit-bot: I haz the power, 2017-02-01 12:36:50]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/13f00a7b6a700f280ec590e654cd...

[cbiesinger, 2017-02-01 19:59:30]

lgtm