patch 9.0.2020: Vim9: islocked() needs more work

Problem:  Vim9: islocked() needs more work
Solution: rework islocked() and remove sync_root
          from get_lval()

closes: #13329

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ernie Rael <errael@raelity.com>
diff --git a/src/structs.h b/src/structs.h
index a221a04..3f461f8 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -4605,16 +4605,12 @@
 } lval_T;
 
 /**
- * This may be used to specify the base typval that get_lval() uses when
- * following a chain, for example a[idx1][idx2].
- * The lr_sync_root flags signals get_lval that the first time through
- * the indexing loop, skip handling  '.' and '[idx]'.
+ * This specifies optional parameters for get_lval(). Arguments may be NULL.
  */
 typedef struct lval_root_S {
-    typval_T	*lr_tv;
-    class_T	*lr_cl_exec;	// executing class for access checking
-    int		lr_is_arg;
-    int		lr_sync_root;
+    typval_T	*lr_tv;		// Base typval.
+    class_T	*lr_cl_exec;	// Executing class for access checking.
+    int		lr_is_arg;	// name is an arg (not a member).
 } lval_root_T;
 
 // Structure used to save the current state.  Used when executing Normal mode