word : transition/dirty/ready simplification
word : transition/dirty/ready simplification

Get rid of VIS.ready.word. We'll use the dirty mechanism instead. Also,
instead of repeatedly checking the condition, we just set a flag,
`fade_in`, at the start of the function, then use that to determine
whether the opacity transitions should happen or not.

agoldst/dfr-browser,agoldst/dfr-browser,agoldst/dfr-browser,agoldst/dfr-browser