Support context-stroke and context-fill SVG painting values

[YakBizzarro]

When a SVG marker is used, and the marker uses the "context-stroke" to inherit the stroke color, instead other properties like dash-array are taken instead. Only the color should be taken (as per spec, and other renderer like Firefox).

Minimal example:

<svg viewBox="0 0 100 20" xmlns="http://www.w3.org/2000/svg">
  <marker
    id="circle"
    markerWidth="6"
    markerHeight="6"
    refX="3"
    refY="3"
    markerUnits="strokeWidth">
    <circle cx="3" cy="3" r="2" stroke="context-stroke" fill="context-fill" />
  </marker>
  <path d="M 10,10 h 50"  style="marker: url(#circle);stroke:#ff0000;stroke-dasharray:6,6;stroke-dashoffset:0" />
</svg> 

in Firefox, that results in the marker color take the the line definition

in Weasyprint on the contrary the color stay the sane, while it inherit the dash style:

[liZe]

Thanks for the report. We don’t support these values (added in SVG 2) at all.

Here’s the related specification.

[YakBizzarro]

ah thanks, I didn't noticed that :) I was fooled by the fact that declaring stroke="context-stroke" results in the dash style being applied, while omitting it the dashes disappears