The missing line is consistently called after ImageContainer::GetWidth/GetHeight (see TransformContextForPainting for example which would be the equivalent code path for the non-webrenderized case).
This fixes the wptest /density-size-correction/density-corrected-image-svg.html when active svg images are enabled.
Depends on D141846
Differential Revision: https://phabricator.services.mozilla.com/D141847
e7634ebbaa