[css-line-grid-1] Spurious / in <img>

[alkorlos]

Fix bikeshed errors.

The command:

bikeshed spec css-line-grid-1\Overview.bs

Throws errors:

LINE 82:3: Spurious / in <img>.
LINE 91:4: Spurious / in <img>.
LINE 128:3: Spurious / in <img>.
LINE 136:3: Spurious / in <img>.
LINE 382:4: Spurious / in <img>.
LINE 389:4: Spurious / in <img>.
LINE 410:4: Spurious / in <img>.
LINE 417:4: Spurious / in <img>.
LINE 650:4: Spurious / in <img>.
LINE 657:4: Spurious / in <img>.
LINE 673:4: Spurious / in <img>.
LINE 680:4: Spurious / in <img>.
LINE 703:4: Spurious / in <img>.
LINE 710:4: Spurious / in <img>.