[css-grid] computed grid-row-start with default span integer #3448
Description
https://drafts.csswg.org/css-grid/#grid-placement-span-int
span && [ <integer> || <custom-ident> ]
If the<integer>is omitted, it defaults to 1. Negative integers or zero are invalid.
grid-row-start "span i" computes to "span 1 i" on Blink/WebKit, but computes to "span i" on Edge/Firefox.
grid-row "span i / auto" computes to "span 1 i / auto" on Blink/WebKit, but computes to "span i / auto" on Edge, empty string on Firefox.
For many properties, the shortest serialization principle often leads to keywords being omitted, but it is unusual for numeric values to be omitted.