bug#19930: 25.0.50; REGRESSION: accessing minibuffer from 2nd frame for same buffer scrolls window back to point of 1st frame

[Drew Adams]

This regression was introduced in Emacs 24.3.  There is no such problem
in Emacs 20 through 24.2.

To reproduce:

1. runemacs.exe -Q --debug-init  -l "onetest.el" -f "1on1-emacs"
   File onetest.el is attached.

   This opens Emacs with a standalone minibuffer frame.

2. Visit a file with some text in it, say foo.el, in the original
   (non-minibuffer) frame displayed.

3. Put point on some function name, e.g. near bob.

3. C-x 5 2, so you now have two frames showing the same buffer.

4. In the frame just created, scroll down a ways (or otherwise move down
   - it is unimportant how you do this), and put point on some other
   symbol (name).

5. M-x grep RET

   As soon as you hit RET, the current window (in the second frame)
   scrolls back to the point position of the first frame.  And if you
   then use M-n to grab a name at point for `grep', it grabs the symbol
   name under the point for the other frame.

In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2014-10-20 on LEG570
Bzr revision: 118168 rgm@gnu.org-20141020195941-icp42t8ttcnud09g
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking=yes,glyphs CPPFLAGS=-DGLYPH_DEBUG=1'