[release-branch.go1] misc/emacs: Restore the window position after a successful gofmt.

««« backport 9d6693456f93
misc/emacs: Restore the window position after a successful gofmt.

This adds restoring the window position so that the buffer doesn't jump around after the erase/copy.

R=sameer
CC=golang-dev
https://golang.org/cl/5981055

»»»

misc/emacs/go-mode.el

@@ -757,10 +757,13 @@ Replace the current buffer on success; display errors on failure."
                     ;; restore window config
                     ;; gofmt succeeded: replace the current buffer with outbuf,
                     ;; restore the mark and point, and discard errbuf.
-		    (let ((old-mark (mark t)) (old-point (point)))
-		      (set-window-configuration currconf)
+                    (let ((old-mark (mark t))
+                          (old-point (point))
+                          (old-start (window-start)))
                       (erase-buffer)
                       (insert-buffer-substring outbuf)
+                      (set-window-configuration currconf)
+                      (set-window-start (selected-window) (min old-start (point-max)))
                       (goto-char (min old-point (point-max)))
                       (if old-mark (push-mark (min old-mark (point-max)) t))
                       (kill-buffer errbuf))