patch 9.0.1718: dict-completion does not respect region

Problem: dict-completion does not respect region
Solution: respect selected region in dict completion

Set do_region to zero as we don't want a complete dump of the matching
words, we want the code to filter them according to the user's selected
region.

closes: #12792
closes: #7025

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: LemonBoy <thatlemon@gmail.com>
diff --git a/src/testdir/test_spell.vim b/src/testdir/test_spell.vim
index 3f7b028..9eecb1e 100644
--- a/src/testdir/test_spell.vim
+++ b/src/testdir/test_spell.vim
@@ -274,8 +274,7 @@
   call assert_equal(['theater'], getline(1, '$'))
   set spelllang=en_gb
   call feedkeys("Stheat\<c-x>\<c-k>\<esc>", 'tnx')
-  " FIXME: commented out, expected theatre bug got theater. See issue #7025.
-  " call assert_equal(['theatre'], getline(1, '$'))
+  call assert_equal(['theatre'], getline(1, '$'))
 
   bwipe!
   set spell& spelllang& dictionary& ignorecase&