Don't recalculate line indexes if number of lines doesn't change.

diff --git a/dlls/user/edit.c b/dlls/user/edit.c
index 9960cef..aae8da9 100644
--- a/dlls/user/edit.c
+++ b/dlls/user/edit.c
@@ -1253,7 +1253,7 @@
 			es->line_count--;
 		}
 	}
-	else
+	else if (delta != 0)
 	{
 		while (current_line)
 		{