Possible redundant keys in Predictions (see PR #996)

[ValerieKenyon]

As I was updating de.js, I noticed the following. I'm giving you all the relevant lines from en.js:
'Changes Chart' seems to have 2 keys, on lines 266 and 315
'Stacked Incomes' seems to have 2 keys, on lines 267 and 318
This may also be an issue for 'Changes' on lines 265 and 302
If we have redundant keys, it probably won't affect anything. But maybe another, more experienced person should take a look at it.

(BTW: I was working from en.js in the google docs, updating to de.js in the google docs, and then creating a new, up-to-date branch. I copied and pasted my German from the google doc into the new branch and tweaked it in VS Code. I also noticed that the en.js in dev branch (and in germanTranslation18_11_13) has a lot more text in it than the en.js google doc, so my updated de.js doesn't actually contain this newer text.)