Merge from origin/emacs-27

02a31c9632 (origin/emacs-27) Minor improvement in the ELisp manual's ...
f750def778 Mention in PROBLEMS the problems with fonts and Uniscribe
082d8a21b1 Minor copyedits in 'line-height' documentation
5b23393bcc ; * src/frame.c (syms_of_frame) <make-pointer-invisible>: ...

diff --cc doc/lispref/display.texi
Simple merge

diff --cc doc/lispref/intro.texi
Simple merge

diff --cc etc/PROBLEMS
Simple merge

diff --cc src/frame.c
Simple merge