Define "svg layout box" vs "css layout box"

[AmeliaBR]

CSSOM View spec has the following inline issue:

The terms CSS layout box and SVG layout box are not currently defined by CSS or SVG.

Distinguishing between SVG elements with and without CSS layout boxes is important for other specifications, as well (e.g., transforms and Resize Observer).

Somewhat related: #360

[dirkschulze]

@AmeliaBR It seems like the following pattern was established to differ between the 2 kind of SVG elements already and is used in many specs:

SVG elements without associated CSS layout box

for SVG elements in the "svg layout box". Isn't that sufficient?

[AmeliaBR]

Isn't that sufficient?

Possibly. We should still clearly define which elements do/don't have an associated CSS layout box, in a way that other specs can link to.

[dirkschulze]

@AmeliaBR Sure, sounds good to have a term description in one of the general sections.