Work around failing getComputedStyle on Facebook.
Work around failing getComputedStyle on Facebook.

getComputedStyle returns null for the channel_iframe document.

nathyong/dactyl,mcarton/vimperator-labs,5digits/dactyl,derenio/vimperator-labs,invl/dactyl,Evidlo/vimperator-labs,paretje/vimperator-labs,seanmorton/vimperator-labs,madand/pentadactyl-pm,airodactyl/dactyl,5digits/dactyl,madand/pentadactyl-pm,airodactyl/dactyl,Kjwon15/dactyl,Sheile/vimperator-labs,nathyong/dactyl,stemar94/vimperator-labs,invl/dactyl,madand/pentadactyl-pm,Kjwon15/dactyl,moonshadow/dactyl,nullren/vimperator-labs,airodactyl/dactyl,moonshadow/dactyl,derenio/vimperator-labs,nullren/vimperator-labs,Kjwon15/dactyl,invl/dactyl,invl/dactyl,moonshadow/dactyl,madand/pentadactyl-pm,airodactyl/dactyl,Kjwon15/dactyl,zklinger/vimperator-labs,nathyong/dactyl,moonshadow/dactyl,invl/dactyl,5digits/dactyl,nathyong/dactyl,Evidlo/vimperator-labs,moonshadow/dactyl,airodactyl/dactyl,paretje/vimperator-labs,seanmorton/vimperator-labs,nathyong/dactyl,airodactyl/airodactyl,Kjwon15/dactyl,5digits/dactyl,Quicksaver/vimperator-labs,airodactyl/airodactyl,Kjwon15/dactyl,moonshadow/dactyl,stemar94/vimperator-labs,airodactyl/dactyl,5digits/dactyl,mcarton/vimperator-labs,zklinger/vimperator-labs,nathyong/dactyl,invl/dactyl,5digits/dactyl,Quicksaver/vimperator-labs,madand/pentadactyl-pm,madand/pentadactyl-pm,Sheile/vimperator-labs