Move generated files to gen/.

test/codegen/expect/extensions.js

Index: test/codegen/expect/extensions.js
diff --git a/test/codegen/expect/extensions.js b/test/codegen/expect/extensions.js
deleted file mode 100644
index 9cfa8105cd720bcd7fea15f38c620abceee3e6e5..0000000000000000000000000000000000000000
--- a/test/codegen/expect/extensions.js
+++ /dev/null
@@ -1,24 +0,0 @@
-dart_library.library('extensions', null, /* Imports */[
-  'dart_sdk'
-], function(exports, dart_sdk) {
-  'use strict';
-  const core = dart_sdk.core;
-  const collection = dart_sdk.collection;
-  const dart = dart_sdk.dart;
-  const dartx = dart_sdk.dartx;
-  const extensions = Object.create(null);
-  extensions.StringIterable = class StringIterable extends collection.IterableBase$(core.String) {
-    new() {
-      this.iterator = null;
-      super.new();
-    }
-  };
-  dart.setSignature(extensions.StringIterable, {});
-  dart.defineExtensionMembers(extensions.StringIterable, ['iterator']);
-  extensions.main = function() {
-    return new extensions.StringIterable();
-  };
-  dart.fn(extensions.main);
-  // Exports:
-  exports.extensions = extensions;
-});