Don't assume window.comments exists during Draftail init
Don't assume window.comments exists during Draftail init

This may break use of Draftail widgets in custom image models, where the usual editor js is not used.
mixxorz/wagtail,torchbox/wagtail,mixxorz/wagtail,rsalmaso/wagtail,wagtail/wagtail,wagtail/wagtail,zerolab/wagtail,zerolab/wagtail,rsalmaso/wagtail,mixxorz/wagtail,thenewguy/wagtail,jnns/wagtail,gasman/wagtail,wagtail/wagtail,wagtail/wagtail,rsalmaso/wagtail,jnns/wagtail,zerolab/wagtail,mixxorz/wagtail,gasman/wagtail,rsalmaso/wagtail,thenewguy/wagtail,thenewguy/wagtail,torchbox/wagtail,jnns/wagtail,zerolab/wagtail,wagtail/wagtail,torchbox/wagtail,thenewguy/wagtail,rsalmaso/wagtail,gasman/wagtail,gasman/wagtail,torchbox/wagtail,thenewguy/wagtail,jnns/wagtail,zerolab/wagtail,gasman/wagtail,mixxorz/wagtail