patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/vim9expr.c b/src/vim9expr.c
index 1fbe05b..7a32974 100644
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -1242,7 +1242,7 @@
 	    item = dict_find(d, key, -1);
 	    if (item != NULL)
 	    {
-		semsg(_(e_duplicate_key_in_dicitonary), key);
+		semsg(_(e_duplicate_key_in_dictionary), key);
 		goto failret;
 	    }
 	    item = dictitem_alloc(key);
@@ -2725,7 +2725,7 @@
 		if (tv2->v_type != VAR_NUMBER)
 		    emsg(_(e_bitshift_ops_must_be_number));
 		else
-		    emsg(_(e_bitshift_ops_must_be_postive));
+		    emsg(_(e_bitshift_ops_must_be_positive));
 		return FAIL;
 	    }