Check whether type parameters are loaded before emitting

test/codegen/functions.dart

Index: test/codegen/functions.dart
diff --git a/test/codegen/functions.dart b/test/codegen/functions.dart
new file mode 100644
index 0000000000000000000000000000000000000000..967f335f40ff3013f77c19b3894dd50aa0dc7b76
--- /dev/null
+++ b/test/codegen/functions.dart
@@ -0,0 +1,14 @@
+List<Foo> bootstrap() {
+  return <Foo>[new Foo()];
+}
+
+typedef B A2B<A, B>(A x);
+
+A2B<Foo, Foo> id(A2B<Foo, Foo> f) => f;
+
+class Foo {
+}
+
+void main() {
+  print(bootstrap()[0]);
+}