<path d> parsing spec needs a special case to not use CSS syntax

[SimonSapin]

When reading the spec literally before this changes, https://svgwg.org/svg2-draft/styling.html#PresentationAttributes specifies that all presentation properties are parsed according to https://svgwg.org/svg2-draft/types.html#presentation-attribute-css-value

For the d property, this means the CSS grammar none | <string>.

The following would be valid:

• <path d="none">
• <path d="'M 100 100 L 300 100 L 200 300 z'"> (not the single quotes)
• <path d="/**/'M 100 100 \L \33 00 100 L 200 300 z'"> (equivalent to the previous)

But <path d="M 100 100 L 300 100 L 200 300 z"> or indeed any SVG 1.1 path would not be valid because they parse as CSS ident and number tokens, not as a <string>.

#320 poposes changing the syntax of the d CSS propery to be even further to the 1.1 attribute syntax.

This does not appear to be an intentional change from SVG 1.1, so this pull request "reverts" it.

[AmeliaBR]

There is an open pull request that is waiting for review about fixing/clarifying the d syntax in attributes vs CSS property: #374

I suspect your concerns are still valid, but if you're able to, it would be helpful if you compared your fixes against those changes.

[SimonSapin]

#374 fixes the same bug that this PR does, in a way that I find satisfactory. It also contains a normative change path(<string>) v.s. <string>, I don’t really have an opinion about that.

[AmeliaBR]

Ok, thanks for checking Simon, and thanks for the effort of the PR even if it turned out to be a duplicate.