Fix staticfiles integration being broken in 1.3.
Fix staticfiles integration being broken in 1.3.

scorphus/webassets,john2x/webassets,heynemann/webassets,JDeuce/webassets,scorphus/webassets,JDeuce/webassets,glorpen/webassets,florianjacob/webassets,wijerasa/webassets,aconrad/webassets,john2x/webassets,aconrad/webassets,aconrad/webassets,0x1997/webassets,heynemann/webassets,heynemann/webassets,glorpen/webassets,wijerasa/webassets,0x1997/webassets,glorpen/webassets,florianjacob/webassets