The spec has been updated so "normal" is stretch for regular grid items,
but for replaced elements it's "start".
It was discussed and agreed on the following CSS WG issue:
We should implement this to pass the following test from the W3C suite:
This has been fixed already in r213480 (bug #169203).
That patch was importing: https://chromium.googlesource.com/chromium/src/+/fad39c71033eea490d8437ca186529c8e87125c2