Merge from origin/emacs-27

75384bd155 Update the doc-view header line
13ab70c80e Avoid breaking Arabic shaping in 'window-text-pixel-size'
e693d97e50 doc-view.el comment clarification
968e85a2ce Update erc documentation about C-c C-b

diff --cc doc/misc/erc.texi
Simple merge

diff --cc lisp/doc-view.el
Simple merge

diff --cc src/xdisp.c
Simple merge