[css-grid] Fix placement for unknown named grid lines

[Manuel Rego Casasnovas]

Placement for undefined named lines is not working as described in the spec:
http://dev.w3.org/csswg/css-grid/#line-placement

Mainly we're not following this statement from the spec:
"If a name is given as a <custom-ident>, only lines with that name are counted. If not enough lines with that name exist, all lines in the implicit grid are assumed to have that name for the purpose of finding this position."

Bug has been already fixed in Blink:
https://bugs.chromium.org/p/chromium/issues/detail?id=442954

We need to port:
https://codereview.chromium.org/1576993003

[Manuel Rego Casasnovas]

Created attachment 273430 [details]
Patch

[Sergio Villar Senin]

Comment on attachment 273430 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=273430&action=review

> Source/WebCore/rendering/style/GridResolvedPosition.cpp:129
> +        return end + numberOfLines - 1;

I think we can do this in a single line.

> Source/WebCore/rendering/style/GridResolvedPosition.cpp:151
> +        return start - numberOfLines + 1;

Ditto

> Source/WebCore/rendering/style/GridResolvedPosition.cpp:167
> +    NamedGridLinesMap::const_iterator it = gridLinesNames.find(position.namedGridLine());

We can use auto for these two.

[Manuel Rego Casasnovas]

Created attachment 273556 [details]
Patch

[Manuel Rego Casasnovas]

Thanks for the review, uploaded new patch for landing applying suggested changes.

[WebKit Commit Bot]

Comment on attachment 273556 [details]
Patch

Clearing flags on attachment: 273556

Committed r197930: <http://trac.webkit.org/changeset/197930>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.