Add regression test for #1533. (#1549)

This was fixed by #1548.

Fix #1533.

Author: munificent

test/tall/regression/1500/1533.unit

@@ -0,0 +1,15 @@
+>>>
+void main() {
+  ComplexSelector(complex.leadingCombinators, [
+    component,
+  ], complex.span, lineBreak: false);
+}
+<<<
+void main() {
+  ComplexSelector(
+    complex.leadingCombinators,
+    [component],
+    complex.span,
+    lineBreak: false,
+  );
+}