patch 8.2.0527: Vim9: function types insufficiently tested

Problem:    Vim9: function types insufficiently tested.
Solution:   Add more tests.  Fix white space check.  Add "test_vim9" target.
diff --git a/src/testdir/Makefile b/src/testdir/Makefile
index 746c849..b2eaecb 100644
--- a/src/testdir/Makefile
+++ b/src/testdir/Makefile
@@ -79,6 +79,16 @@
 		exit 1; \
 	fi
 
+# Run only tests specific for Vim9 script
+test_vim9:
+	rm -f test_vim9_*.res test.log messages
+	@MAKEFLAGS=--no-print-directory $(MAKE) -f Makefile $(TEST_VIM9_RES) VIMPROG=$(VIMPROG) XXDPROG=$(XXDPROG) SCRIPTSOURCE=$(SCRIPTSOURCE)
+	@cat messages
+	@MAKEFLAGS=--no-print-directory $(MAKE) -f Makefile report VIMPROG=$(VIMPROG) XXDPROG=$(XXDPROG) SCRIPTSOURCE=$(SCRIPTSOURCE)
+	@if test -f test.log; then \
+		exit 1; \
+	fi
+
 RM_ON_RUN = test.out X* viminfo
 RM_ON_START = tiny.vim small.vim mbyte.vim mzscheme.vim test.ok benchmark.out
 RUN_VIM = VIMRUNTIME=$(SCRIPTSOURCE) $(VALGRIND) $(VIMPROG) -f $(GUI_FLAG) -u unix.vim $(NO_INITS) -s dotest.in