bug#16461: 24.3.50; electric eats too much

[Juri Linkov]

In Text mode typing RET on a formfeed character ^L deletes it.
The presence of ^L means it's here on purpose, so RET should keep it.

electric-indent-post-self-insert-function calls indent-according-to-mode
that uses special casing for indent-relative (that is the default
indent-line-function in text-mode).  I don't understand why it
calls ^L-eating indent-line-to instead of indent-relative
but without this special casing, indent-relative works fine
and doesn't eat ^L.