patch 8.2.1395: Vim9: no error if declaring a funcref with lower case letter

Problem:    Vim9: no error if declaring a funcref with a lower case letter.
Solution:   Check the name after the type is inferred. Fix confusing name.
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 746983d..7e1e16a 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -53,8 +53,8 @@
   let RetThat: func = g:atrue ? RetOne : RetTwo
   assert_equal(function('len'), RetThat)
 
-  let x = FuncOne
-  let y = FuncTwo
+  let X = FuncOne
+  let Y = FuncTwo
   let Z = g:cond ? FuncOne : FuncTwo
   assert_equal(123, Z(3))
 enddef
@@ -132,8 +132,8 @@
 
   " missing argument detected even when common type is used
   call CheckDefFailure([
-	\ 'let x = FuncOne',
-	\ 'let y = FuncTwo',
+	\ 'let X = FuncOne',
+	\ 'let Y = FuncTwo',
 	\ 'let Z = g:cond ? FuncOne : FuncTwo',
 	\ 'Z()'], 'E119:')
 endfunc