bug#20846: 24.4; Electric-indent-mode does not call indent-line-function after hitting RET inside a comment

[Stefan Monnier]

> Then that sentence is misleading and should be rephrased, because my
> reading of it is that it clearly states that auto-indentation inside
> strings is generally impossible, and expects the implementations to
> behave like that.

[ It does not say intend to that.  It says to return `noindent` when
  indentation is impossible and gives "inside a string" as an example of
  a reason why indentation might not be possible.  ]

In any case, this argues in favor of `electric-indent-mode` calling
`indent-line-function` even when we're inside a comment.

The (nth 8 (syntax-ppss)) test has been in `electric-indent-mode` from
the very beginning, but I must say I can't remember why I put it in,
I think it was a mistake and we should remove it.

Especially since it can be re-added easily by configuring
`electric-indent-functions` for those modes/users who prefer it that way.


        Stefan