Skip default action in hideHelpDialog. Fixes #126.
Skip default action in hideHelpDialog. Fixes #126.

Return values of event handlers added with addEventListener are ignored,
so returning `false` doesn't help.
Instead preventDefault has to be called on the event that is passed on
to the handler.

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