patch 8.2.2079: Vim9: cannot put a linebreak before or after "in" of ":for"

Problem:    Vim9: cannot put a linebreak before or after "in" of ":for".
Solution:   Skip over linebreak.

src/testdir/test_vim9_script.vim

@@ -1849,6 +1849,28 @@ def Test_for_loop()
     concat ..= str
   endfor
   assert_equal('onetwo', concat)
+
+  var total = 0
+  for nr in
+      [1, 2, 3]
+    total += nr
+  endfor
+  assert_equal(6, total)
+
+  total = 0
+  for nr
+    in [1, 2, 3]
+    total += nr
+  endfor
+  assert_equal(6, total)
+
+  total = 0
+  for nr
+    in
+    [1, 2, 3]
+    total += nr
+  endfor
+  assert_equal(6, total)
 enddef
 
 def Test_for_loop_fails()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2079,
 /**/
     2078,
 /**/

src/vim9compile.c

@@ -6486,6 +6486,7 @@ compile_for(char_u *arg_start, cctx_T *cctx)
     char_u	*arg_end;
     char_u	*name = NULL;
     char_u	*p;
+    char_u	*wp;
     int		var_count = 0;
     int		semicolon = FALSE;
     size_t	varlen;
@@ -6503,13 +6504,19 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	var_count = 1;
 
     // consume "in"
+    wp = p;
     p = skipwhite(p);
-    if (STRNCMP(p, "in", 2) != 0 || !VIM_ISWHITE(p[2]))
+    if (may_get_next_line_error(wp, &p, cctx) == FAIL)
+	return NULL;
+    if (STRNCMP(p, "in", 2) != 0 || !IS_WHITE_OR_NUL(p[2]))
     {
 	emsg(_(e_missing_in));
 	return NULL;
     }
-    p = skipwhite(p + 2);
+    wp = p + 2;
+    p = skipwhite(wp);
+    if (may_get_next_line_error(wp, &p, cctx) == FAIL)
+	return NULL;
 
     scope = new_scope(cctx, FOR_SCOPE);
     if (scope == NULL)