Move generated files to gen/.

test/codegen/expect/script.js

Index: test/codegen/expect/script.js
diff --git a/test/codegen/expect/script.js b/test/codegen/expect/script.js
deleted file mode 100644
index 472596a2801b7f3a6aa62f88311f6364b45106a2..0000000000000000000000000000000000000000
--- a/test/codegen/expect/script.js
+++ /dev/null
@@ -1,17 +0,0 @@
-dart_library.library('script', null, /* Imports */[
-  'dart_sdk'
-], function(exports, dart_sdk) {
-  'use strict';
-  const core = dart_sdk.core;
-  const dart = dart_sdk.dart;
-  const dartx = dart_sdk.dartx;
-  const script = Object.create(null);
-  script.main = function(args) {
-    let name = args[dartx.join](' ');
-    if (name == '') name = 'world';
-    core.print(`hello ${name}`);
-  };
-  dart.fn(script.main, dart.void, [core.List$(core.String)]);
-  // Exports:
-  exports.script = script;
-});