[css-flexbox] flex-grow property should be animatable

[Carlos Alberto Lopez Perez]

The flex-grow property must be animatable

https://drafts.csswg.org/css-flexbox/#flex-grow-property

Here its a simple test case: https://codepen.io/cl0p3z/pen/yLNrNyN

Works on Chrome and Firefox. Fails on WebKit.

This its tested by WPT css/css-flexbox/animation/flex-grow-interpolation.html

[Sergio Villar Senin]

Created attachment 411314 [details]
Patch

[Antoine Quint]

Comment on attachment 411314 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=411314&action=review

r+ assuming EWS bots are happy as well, thanks for adding this.

> Source/WebCore/rendering/style/RenderStyle.h:1104
> +    void setFlexGrow(float f) { float v = std::max<float>(f, 0.f); SET_NESTED_VAR(m_rareNonInheritedData, flexibleBox, flexGrow, v); }

Perhaps spell out what `v` stands for here. Since you're clamping, perhaps call that out in the variable name.

[Sergio Villar Senin]

Created attachment 411321 [details]
Patch for landing

[Sergio Villar Senin]

Committed r268516: <https://trac.webkit.org/changeset/268516>

[Radar WebKit Bug Importer]

<rdar://problem/70325825>