Make check for document.body more robust.
Make check for document.body more robust.

document.body.nodeName is not always 'body' -- it might be 'frameset',
for instance.

poacher2k/vimium,bkudria/vimium,elderbas/vimium,PickRelated/vimium,Aleroniponi/vimium,dimatter/vimium,smblott-github/vimium,tuchangwei/vimium,poacher2k/vimium,dimatter/vimium,crazypenguincode/vimium,Lw-Cui/vimium,csmalin/vimium,willsALMANJ/vimium,elderbas/vimium,philc/vimium,douglas-larocca/vimium,cyrixhero/vimium,smblott-github/vimium-smblott,poacher2k/vimium,mrmr1993/vimium,wildeyes/vimium,jb55/vimium-plus,Robinson10240/vimium,PrestanceDesign/vimium,justalittlenoob/vimium,borgified/vimium,willsALMANJ/vimium,zhangmin510/vimium,hhsue/vimium,bkudria/vimium,tuchangwei/vimium,Aleroniponi/vimium,philc/vimium,borgified/vimium,willsALMANJ/vimium,gdh1995/vimium,elegantwww/vimium,douglas-larocca/vimium,philc/vimium,wildeyes/vimium,smblott-github/vimium,Robinson10240/vimium,gdh1995/vimium,VPashkov/vimium,wildeyes/vimium,zhangmin510/vimium,tuchangwei/vimium,llimllib/vimium,jb55/vimium-plus,douglas-larocca/vimium,PrestanceDesign/vimium,elegantwww/vimium,VPashkov/vimium,decaffeinate-examples/vimium,elegantwww/vimium,justalittlenoob/vimium,gdh1995/vimium,PrestanceDesign/vimium,Lw-Cui/vimium,cyrixhero/vimium,mrmr1993/vimium,VPashkov/vimium,Aleroniponi/vimium,mrmr1993/vimium,cyrixhero/vimium,zhangmin510/vimium,justalittlenoob/vimium,crazypenguincode/vimium,smblott-github/vimium,decaffeinate-examples/vimium,PickRelated/vimium,csmalin/vimium,Robinson10240/vimium,bkudria/vimium,PickRelated/vimium,shaung/vimium,dimatter/vimium,csmalin/vimium,decaffeinate-examples/vimium,smblott-github/vimium-smblott,hhsue/vimium,elderbas/vimium,borgified/vimium,hhsue/vimium,Lw-Cui/vimium