Hook up full list literal type inference logic.

pkg/front_end/testcases/inference/list_literals_top_level.dart

Index: pkg/front_end/testcases/inference/list_literals_top_level.dart
diff --git a/pkg/front_end/testcases/inference/list_literals_top_level.dart b/pkg/front_end/testcases/inference/list_literals_top_level.dart
index d570a4bf8c2f551c2326c011ed93a023c1398588..58c36650730d5c1b19e81b940b3e810408387aec 100644
--- a/pkg/front_end/testcases/inference/list_literals_top_level.dart
+++ b/pkg/front_end/testcases/inference/list_literals_top_level.dart
@@ -19,3 +19,8 @@ test2() {
   x2.add(4.0);
   List<int> y = /*info:ASSIGNMENT_CAST*/ x2;
 }
+
+main() {
+  test1();
+  test2();
+}