Generate out.precompiled.js, not precompiled.js.

dart/tests/compiler/dart2js/unneeded_part_js_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Test that no parts are emitted when deferred loading isn't used.
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'memory_source_file_helper.dart';
 
@@ skipping 13 matching lines @@
   var provider = new MemorySourceFileProvider(MEMORY_SOURCE_FILES);
   void diagnosticHandler(Uri uri, int begin, int end,
                          String message, Diagnostic kind) {
     if (kind == Diagnostic.VERBOSE_INFO) {
       return;
     }
     throw '$uri:$begin:$end:$message:$kind';
   }
 
   EventSink<String> outputProvider(String name, String extension) {
-    if (name != '' && name != 'precompiled') {
-      throw 'Attempt to output file "$name.$extension"';
-    }
+    if (name != '') throw 'Attempt to output file "$name.$extension"';
     return new NullSink('$name.$extension');
   }
 
   Compiler compiler = new Compiler(provider.readStringFromUri,
                                    outputProvider,
                                    diagnosticHandler,
                                    libraryRoot,
                                    packageRoot,
                                    []);
   asyncTest(() => compiler.run(Uri.parse('memory:main.dart')).then((_) {
@@ skipping 12 matching lines @@
 
 main() {
   var x = fisk;
   if (new DateTime.now().millisecondsSinceEpoch == 42) {
     x = new Greeting(\"I\'m confused\");
   }
   print(x.message);
 }
 """,
 };