driver: Follow-up to grandparent: Have all test suite entry points declare the mock $region_highlight.

tests/generate.zsh already does this.

tests/test-perfs.zsh

@@ -48,6 +48,7 @@
 }
 
 # Load the main script.
+typeset -a region_highlight
 . ${0:h:h}/zsh-syntax-highlighting.zsh
 
 # Activate the highlighter.

tests/test-zprof.zsh

@@ -29,6 +29,7 @@
 # -------------------------------------------------------------------------------------------------
 
 # Load the main script.
+typeset -a region_highlight
 . ${0:h:h}/zsh-syntax-highlighting.zsh
 
 # Activate the highlighter.