Ensure that single-item tree-sitter lists are difftastic lists

This is important when executing tree-sitter queries, as highlighting
queries tend to target leaf nodes. Flattening the tree loses that.

This may also lead to more accurate diffing logic in some examples,
but I haven't found any obvious cases.

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 Improved handling of paired delimiters, particularly in C, C++ and C#.
 
+Fixed a rare issue where single-item lists were flattened.
+
 ### Integration
 
 Added support for Mercuial, see [this section in the

src/tree_sitter_parser.rs

@@ -338,7 +338,7 @@ fn syntax_from_cursor<'a>(
         // Treat nodes like string literals as atoms, regardless
         // of whether they have children.
         atom_from_cursor(arena, src, nl_pos, cursor)
-    } else if node.child_count() > 1 {
+    } else if node.child_count() > 0 {
         list_from_cursor(arena, src, nl_pos, cursor, config)
     } else {
         atom_from_cursor(arena, src, nl_pos, cursor)