[CSS Regions] The box decorations of an element overflowing a region should be clipped at the border box, not the content box

[Radu Stavila]

Currently, the contents of the box is correctly clipped by the region at the border box. However, the box decorations are clipped at the content box.

[Radu Stavila]

Created attachment 224368 [details]
Patch

[Andrei Bucur]

Comment on attachment 224368 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=224368&action=review

> Source/WebCore/rendering/RenderRegion.cpp:525
>          mappedRect.intersect(flowThreadPortionRect());

I think the correct order of operations is to expand the flowThreadPortionRect() with the paddings and then intersect. This way:
1. You expand only when actually clipping
2. You don't expand a rectangle already intersected with the flowThreadPortionRect() that doesn't need the extra space to display correctly.

> Source/WebCore/rendering/RenderRegion.cpp:533
> +        if (isFirstRegion()) {

This should be startRegion.

> Source/WebCore/rendering/RenderRegion.cpp:543
> +        if (isLastRegion()) {

This should be lastRegion.

[Radu Stavila]

Created attachment 224377 [details]
Patch

[Andrei Bucur]

Comment on attachment 224377 [details]
Patch

r=me. Before committing, please update the CL with the new helper you implemented. Thanks!

[Radu Stavila]

Created attachment 224381 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 224381 [details]
Patch for landing

Clearing flags on attachment: 224381

Committed r164231: <http://trac.webkit.org/changeset/164231>